Bibliographies

1

AARNIO, M., BERGSTRÖM, I., HILDEN, M., PESONEN, A., TAMMELIN, J. & TAMMINEN, T. 1978: Nuotta- ja verkkokalastuksen vertailua Keiteleellä.
- Ohjattu järvitutkimus 1978. Helsingin yliopisto, limnologian laitos, laudatur-harjoituskurssi. 24 pp. (S)*

* The capital letter in brackets behind the title indicates the contributor of this abstract. For explanation see page 2

Title: Comparison of the seine and gillnet fisheries in Lake Keitele.

Fishing gear: Fleet of seven gillnets from monofilament, meshsize 12, 15, 20, 25, 35, 45, 60 mm (bar length) and one trammel net from twisted nylon, meshsize 75 mm, height of each net 1.8 m and length 27 m. Seine net, height 8 m, length 180 m, meshsize in the bag of the seine 8 mm.

Fishing conditions: Data from June and July 1978, gillnets and trammel net used overnight as bottom nets, depth 2–6 m, seine hauling mostly in daytime, depth in the seining ground 1–15 m, both gears used in the same areas.

Species fished: Perch (Perca fluviatilis): length range 10–21 cm (gillnets), 5 – 18 cm (seine net), height of head 9 – 39 mm and height of body 14 – 50 mm (gillnets, meshsizes 12 – 25 mm). Roach (Rutilus rutilus); length range 10 – 23 cm (gillnets), 11 – 22 cm (seine net), height of head 9 – 33 mm and height of body 14 – 59 mm (gillnets, meshsize 12 – 25 mm). Whitefish (Coregonus lavaretus (L.)) s.str. and C. oxyrhynchus (L.)), length range 17 – 33 cm (gillnets), 10 – 29 cm (seine net), number of gillrakers 25 – 48.

Bycatch: Smelt, bleak, vendace, pike, ruffe, burbot, white bream and rainbow trout, catch with the fleet of nets 20,5% and with seine 23,0 % from the total weight of the catch.

Selective effects: In the catch with seine more small species like vendace and smelt, length distribution of perch different in the catches with gillnets and with seine, mean lengths of perch and roach significantly different in catches with different meshsizes, linear correlations between mean length and meshsize (meshsizes 12 – 25 mm), correlation factors 0.87 (perch) and 0.88 (roach), linear correlation between the mean of head and body height and meshsize, (meshsizes 12 – 25 mm), correlation factors 0.85 (perch) and 0.88 (roach).

Type of water: Lake Keitele in the Middle Finland, the research area was a strait in Lake Keitele, surface area of the strait 4 km² and mean depth 4.5 m.

2

ANTTILA, R. & VIRTANEN, E. 1971: Verkkohavaksen solmuväli ja kalan pituus.
Vesiensuojelulaboratorion tiedonantoja 7, 1–25 (S)

Title: Meshsize of gillnet and fish length.

Fishing gear: Fleet of nine gillnets from monofilament (meshsizes 12, 17, 20, 25, 27, 35, 40, 45, 60 mm, bar length), and one trammel net from twisted nylon (meshsize 75 mm), diameter monofilament from 0.15 to 0.20 mm, height of nets 1.7 m (meshsize from 12 to 60 mm) and 1.7 m (meshsize 75 mm), length of all nets 30 m.

Fishing conditions: Data from years 1969 and 1970.

Species fished: Roach (Rutilus rutilus), length range 7–31 cm, white bream (Blicca bjoerkna), l. r. 8–28 cm, bream (Abramis brama), l. r. 8–43 cm, perch (Perca fluviatilis), l.r. 4–32 cm, pikeperch (Lucioperca lucioperca), l.r. 10–57 cm.

Bycatch: Other species not reported.

Selective effects: Length range of fish caught smaller with meshsizes 12–27 mm than with larger meshsizes, variation in length of pikeperch greater than in length of other species, average lengths of roach, bream, white bream and perch in various nets are of the same order of magnitude.

Type of water: The sea area off Helsinki.

3

BACKIEL, T., KORYCKI, A. 1972: Selektywnosc wontonow na przykladzie polowow ploci i wzdregi.
Rocz. Nauk Rol., ser. H, t. 94, 1, 7–22. (SW)

Title: Selectivity of gillnets on the example of roach and rudd catches.

Fishing gear: Impregnated cotton gillnets, meshsizes 2.5, 2.8, 3.0, 3.5, 4.0, 4.5 cm. Three nets connected to form fences of the same meshsize from the lake centre to a narrowing connecting this lake part with another one.

Fishing conditions: Catches in Lake Klebark, in 1962 – 1964, in two periods in each year: at the turn of May and June, and at the turn of August and September. Totally 135 days of fishing. The nets were lifted each morning, the fishes removed, and the nets set again. Each fish was measured and weighed.

Species fished: Roach: 21 length classes at 1 cm intervals, within the range 10 – 30.9 cm. Totally 6934 fishes were measured. The most numerous length classes were:

17.0 – 17.9 cm - 790 fishes
18.0 – 18.9 cm - 786 fishes
19.0 – 19.9 cm - 707 fishes

Rudd: 17 length classes within the length range 11.0 – 27.9 cm. A total of 1997 fishes were measured. The most numerous length classes were:

15.0 – 15.9 cm - 267 fishes
16.0 – 16.9 cm - 237 fishes
17.0 – 17.9 cm - 237 fishes

Bycatch: -

Selective effects: -

General remarks: Equations were given for the approximated relations between the length (1) of fishes which can be caught with maximal effectivity and meshsize (m) :
roach: 1 = 2.74 + 5.298 m
rudd: 1 = 11.34 m - 0.91 m² - 7.03
Fishing with sets of gillnets with meshsizes 2.5, 3.0, 3.5, 4.0 and 4.5 cm appeared to be practically non-selective toward roach 17 – 25 cm long. The same set was selective toward rudd.

4

CIEPIELEWSKI, W. 1974: Selektywnosc wontonow sielawowyc
Rocz. Nauk Rol., ser. H, t. 96, 1, 17 – 29. (SW)

Title: Selectivity of gillnets for the catches of Coregonus albula

Fishing gear: A set of gillnets made of steelon fabric Td 80/3, with meshsizes 18, 22 and 24 mm, height of each net 8 m, length 45 m. A set of gillnets made of steelon cord, meshsize 26 mm, height of nets 4 m.

Fishing conditions: Gillnets were set from May till December, once or twice in a month, in surface water layer (0 – 10 m). Studies were carried out in Lake Maroz (area 332,5 ha) in 1967 – 1970. Water temperatures were measured and oxygen content determined. Due to bad oxygen conditions in the lake vendace did not occur below the surface 15 m water layer.

Species fished: Vendace: 13 length classes within the range of 15 – 27 cm (i.e. 14.1 – 15 cm and 26.1 – 27 cm). Only a few fishes were caught in the nets made of steelon cord, so these materials were not analysed.

Bycatch: -

Selective effects: Net setting coefficients were similar for both types of nets used, i.e. vertical net setting coefficient = 0.45, horizontal one = 0.89.

Type of water: Lake Maroz.

General remarks: Holt's model was taken advantage of to calculate selectivity of vendace gillnets. Numerical values of the selectivity curve were as follows:

length 14.1–15.0 to 16 to 17 to 18 to 19 to 20 to 21 to 22 to 24 to 25

classes S_ij 0.2541 0.7118 1.1225 1.1922 1.3301 1.6676 1.7537 1.3674 0.3100 0.0975

5

CIEPIELEWSKI, W. 1981: Population of pike (Esox lucius) in pond type Lake Warniak.
Ekol. Pol., 29, 1, 29 – 51. (SW)

Title: See above

Fishing gear: Specially constructed seine net with wings 300 m, adapted to the lake unter study.

Fishing conditions: Catches in autumn 1969 – 1978 in Lake Warniak: (38.4 ha, average depth 1.5 m). Two fishing grounds fished daily.

Species fished: Pike: specimens longer than 30 cm. Maximal catch recorded 23 kg/ha, minimal less than 1 kg/ha. Average weight of the fish caught was the highest in years with minimal yields. Catastrophic decrease of catches took place in 1977 and 1978. Specimens caught in length classes 34 – 42 cm, usually 2 – 3 years old. Virtual population changed from a few hundred to two thousand specimens. In 1977 the virtual population dropped to 74 individuals. Calculation showed that in 1969 – 1976 pike biomass varied from 10.0 to 40.6 kg/ha annually. Production in the years when 2 and 3 years old specimens predominated was high, exceeding even average biomass: 6.6 – 41.6 kg/ha annually. Sex ratio in the dominating age groups (2 – 4 years of age) was 1 : 1. Older age groups were predominated by females.

Bycatch: -

Selective effects: -

Type of water: Lake Warniak, Eutropic lake of pond type, with the bottom overgrown by submerged vegetation, reed belt around the lake.

General remarks: Disappearance of submerged vegetation in course of the studies resulted in drastic decrease of pike numbers.

6

DABROWSKI, B., LEOPOLD, M., NOWAK, W. 1964: Struktura gatunkowa potowow przywloka.
Rocz.Nauk Rol.,ser. E, t. 83, 4, 631 – 644 (SW)

Title: The Species composition of catches with summer seine with bags.

Fishing gear: Summer seine.

Fishing conditions: Seine catches carried out since July till December 1963. Fishing yield amounted to 157,5 kg for small lakes, 253.3 kg for big lakes, and 207.0 kg/fishing day on the average.

Species fished: Species composition of the catch: roach - 44.76 %, pike - 12.86 bream - 12.41 %, perch - 11.01 %, white bream - 9.66 %. In particular months the mentioned fish species constituted altogether from 87 to 90 % of the fish catch.

Bycatch: Species, the catches of which did not exceed 5 %, of no importance. These were: tench, pikeperch, crucian carp, vendace, whitefish, eel, carp - totally 9.3 %.

Selective effects: -

Type of water: Lakes of Mazurian Lakeland, divided into 3 groups: 0 – 80 ha, 80 – 500 ha, over 500 ha.

General remarks: Seine net is not considered to be species selective, but it can be used to regulate stocks of particular fish species.

7

DEMBINSKI, W., MAYER, I., SWIERZOWSKI, A. 1978: Selektywnosc elektrycznej tuki wegorzowej.
Rocz. Nauk Rol.,ser. H.,t. 98, 4, 115–127 (SW)

Title: Selectivity of an electric eel pair net.

Fishing gear: Electric eel pair net type 24/15. Length of headline - 24 m. Horizontal opening of the inlet during net work about 12 m, vertical opening - 2 – 3 m. Two codends studied, with meshsize 14.1 mm when dry (14.8 mm wet) and 25.3 mm (25.6 mm wet). Length of mesh side in the cover net 8 mm. Meshsize established according to Polish normatives PN-68/P-85033 (30 rows of 10 meshes, at loading of 3 % of the resistance to bursting). Headline and bottom line equipped with the electrodes (copper wire Ø 6 mm²). Power supply from an autotransformer PAB-2-1/230 (50 Hz, 230 V, 8.7 A, 2.0 KVA). Power used: 130 – 190 V, 21 - 15 A.

Rys. 1. Schemat bucowy elektrycznej tukl wegorzowej typu 24/15, w której zastosowano worki o wielkości oczka sieci 14,1 i 25,3 mm oraz okrywę o wielkości oczka 8 mm

Fig. 1. Diagram of construction of a 24/15 type eel pair net in which bags of 14.1 and 25.3 mm mesh are used, with cover of 8 mm mesh

Fishing conditions: The net hauled from two motor-boats at a speed of 0.3 m/sec. One haul lasted from 20 to 60 min. Studies carried out since June till November 1972 on two lake complexes:

- coastal Lake Gardno (area 5469 ha, average depth 1.3 m), periodically high conductivity of water, up to 1400 μS (in this lake codend of meshsize 14.1 mm was used);

- Mazurian lakes: Lake Sniardwy (area 11383 ha, average depth 5.8 m), Lake Tyrklo (area 236 ha, average depth 9.7 m), Lake Orzysz (area 1085 ha, average depth 6.9 m). Lake Wierzbiny (area 75 ha, average depth 2.8 m). Electrolytic conductivity in these lakes amounted to 200 – 400 μS/cm (codend of 25.3 mm meshsize was used).

Species fished: Eel; Lake Gardno - average length 58.6 ± 10.5 cm; Mazurian lakes - average length 58.3 ± 10.3 cm.

Rys. 2. Procentowy rozkład liczebności w poszczególnych klasach długości węgorza złowionego elektryczną tuką węgorzowaą w przymorskim jeziorze Gardno (N = 413) i w kilku Jeziorach Mazurskich (N = 1121) przy rozmiarze oczka w okrywie 8 mm (n = liczcbność węgorza niewymiarowego — poniżej 300 g)

Fig. 2. Percental distribution of number of eel according to class lengths. Catches of eel by means of an electric eel pair net in sea coast lake Gardno (N = 413) and in several lakes of the Mazurian Lake Region (N = 1121) and with a mesh of 8 mm in the cover (n = number of eel of less than 300 g)

Rys. 3. Zależność ciężaru od długości ciała węgorzy z przymorskiego jeziora Gardno (N = 413) i kilku Jezior Mazurskich (N = 1121)
Fig. 3. Correlation between weight and length of eel from the sea coast Lake Gardno (N = 413) and from several Mazurian Lakes (N = 1121)

Bycatch: none

Selective effects:-

Type of water: Coastal Lake Gardno connected with the Baltic Sea. Mazurian lakes typical of the lakes in the biggest lake area in Poland i.e. Mazurian Lakeland (post-glacial lakes).

General remarks: Studies delt with selectivity of the codends (bags) of the eel pair net. In the bags (codends) with meshsize 14.1 mm length of eels in 50 % selectivity point amounted to L₅₀ = 61.2 cm, at SF = 24.2.

8

DENSEN, van W.L.T.: Gillnet selectivity to pikeperch, Stizostedion lucioperca, and perch, Perca fluviatilis, caught mainly wedged Journal Aquaculture and Fisheries Management (in press) (VD)

Title: Gillnet selectivity to pikeperch, Stizostedion lucipoperca, and perch, Perca fluviatilis, caught mainly wedged.

Fishing gear: 1978 anchored bottom nets with 25, 30, 35 mm bar mesh. Material PA multifilament, length 20 m, depth 1.5 m.
1979–1985 anchored bottom nets of PA multifilament (210/3). Colour white, length 50 m, depth 1.25 m, bar mesh 48, 50, 51, 55, 60, 65 mm. Hanging coefficient varied between 0.35 to 0.47. Nets were fitted out with vertical connection lines (length 1.1 m) between floatline and sole rope.

Fishing conditions: nets set overnight in summer in 1978 during 34 settings, all-year round from 1979–1985 in 149 settings.

Fishing effort: Meter net length times nights: in 1978 2680 m, from 1979–1985 29850 m.

Species fished: Pikeperch (Stizostedion lucioperca) length range (fork length) 219 – 770 mm, ratio girth to fork length G = 0.5971 L_f - 47.2 Perch (Perca fluviatilis) length range (fork length) 186 – 314 mm, ratio girth to fork length G = 0.6734 L_f - 5.4.

Bycatch: none mentioned

Selective effects: Pikeperch: ratio girth to mesh perimeter from 1.12 to 1.25 depending on the body condition

perch: ratio girth - mesh perimeter 1.22.

Type of water: Shallow low-land lake with a mean depth of 1.5 m, in the south-western part some deeper areas, up to 10 m. Name: Tjeukemeer

General remarks:

9

ELSTER, H. J.: 1944 Über das Verhältnis von Produktion, Bestand, Befischung und Ertrag sowie die Möglichkeiten einer Steigerung der Erträge, untersucht am Beispiel der Blaufelchenfischerei des Bodensees. Z.f.Fischerei 42, 169–357. (Lö)

Title: About the relation of production, stock, fishing effort and yield and the possibilities to increase the yields; investigated on the example of the whitefish fishery of Lake Constance.

Fishing gear: a. drifting gillnet - sets from cotton, meshsizes 32, 36, 38, 40 mm.

b. seine net (Klusgarn) with different meshsize in the bag.

Fishing conditions: catches from 1931 – 1942.

Species fished: Coregonus lavaretus wartmanni

Bycatch: None mentioned

Selective effects: selection range (fish length) of meshsizes in gillnets compared to seine net catches. Maximum catchability of different meshsizes in different months.

Type of water: Lake Constance F.R.G. in its oligotrophic state. Surface area: 476 km², max. depth: 252 m, mean depth: 100 m, exploitation mainly by professional fishermen.

General remarks: Main goal of the investigation was to:

1. investigate the facts affecting the fish production,

2. determine the fishing effort (fishing mortality 88%, since 1892 a tenfold increase in fishing effort)

3. give data about the horizontal and vertical fish distribution, growth and nutrition

for an appropriate fishery management of the lake.

10

HAMMAR, J. & O. FILIPSSON: Ecological testfishing with Lundgren gillnets of multiple meshsize, the Drottningholm technique modified for Newfoundland arctic char populations. Rep.Inst.Freshw.Res., Drottningholm (E) (In print)

Fishing gear: “Lundgrens” gillnet of multiple meshsize. Each net contains either meshsize from 10–75 mm or 6.25–75.0 mm (knot to knot).

Fishing conditions:

Species fished: Arctic char, Brook trout, Lake trout, Atlantic salmon, Rainbow smelt, White sucker, Three-spined stickleback.

Bycatch:

Selective effects: Description of standardized test fishing with Lundgrens multiple meshsize gillnets and the species selectivity.

Type of water: From small and shallow ponds (less than 100 ha) in alpine regions to deep river canyons and lakes (larger than 18000 ha) in insular Newfoundland and Labrador.

General remarks:

11

HAMRIN, S.F. 1979: Populationsdynamik, vertikalfördelning och födoval hos siklöja Coregonus albula L., i sydsvenska sjöar. (English summary.) Ph.D. thesis.Limnol.Inst.Univ. Lund. 195 p. (E)

Title: The population dynamics, vertical distribution and food choice of cisco (Coregonus albula L.) in south-swedish lakes.

Fishing gear: Monofilament gillnets with meshsize 10.75, 15.0 and 16.25 mm (knot to knot).

Fishing conditions:

Species fished: Cisco (Coregonus albula)

Bycatch:

Selective effects: Gillnets were placed in the epilimnion, metalimnion and hypolimnion. The length distribution and weight of the catch of each depth were weighted with the share of the total volume of the lake. The length distribution of the catch was also corrected according to the selectivity of the meshsizes used.

Type of water: The investigation was conducted in the south-swedish lakes: Bolmen, Ivösjön, Fegen, Hurven, Skärlen and Gyltigesjön. All of them with different limnological qualities.

General remarks:

12

HAVINGA, B., DEELDER, C.L. 1949 The Relation between the Size of Meshes of Gill Nets and the Size of Lucioperca sandra in the Catches Rapport Procès-Verbaux CXXV, 59–62 (VD)

Fishing gear: mesh lengths (diagonals of meshes stretched lengthwise) 100, 105, 110 mm material: fine linen netting garn, length of nets 500 meshes.

Fishing effort: 25 nets of every kind in total. 4 nets of one meshsizes combined with same number of the other meshsizes. Fishing lasted from December 1947 til March 1948.

Species fished: Pikeperch (Lucioperca sandra), length from 35 to 75 cm.

Bycatch: none mentioned

Selective effects: Optimum fishing capacity at 100 mm for fishes of 45 – 54 cm, at 105 for fishes of 46,5 – 54,5 cm and 110 mm for fishes of 49 – 56 cm.

Type of water: Iysselmeer

General remarks: Experiments carried out to find out the appropriate meshsize for the protection of fishes under 45 cm by means of legal minimum meshsize.

13

HANNULA, P. 1982: Verkkosarjan valikoivuus ahvenelle ja särjelle. - Pro-gradututkielma, Helsingin yliopisto, eläintieteen laitos. 55 pp. (S)

Title: Selectivity of the gillnet set for perch and roach.

Fishing gear: Fleet of eight gillnets from monofilament (meshsizes 12, 15, 20, 25, 30, 35, 45, 60 mm, bar length) and one trammel net from twisted nylon (meshsize 75 mm), diameter monofilament from 0.15 to 0.20 mm, height of all nets 1.8 m and length 30 m.

Fishing conditions: Data from April 1975 to January 1976 and from September 1980 to March 1982, nets used overnight as bottomnets.

Species fished: Perch (Perca fluviatilis), length range 10.2–31.8 cm, roach (Rutilus rutilus), 1.r. 12.8 – 30.3 cm.

Bycatch: Other species not reported

Selective effects: Linear regression of length to maximum and head girths both for perch and roach, modal lengths of perch 10.5, 12.5, 15.4, 18.9, 22.3 and 23.4 cm (meshsizes from 12 to 35 mm), expected length distributions predicted from girth measurements nearly similar in shape both for perch and roach, widths and heights of expected length distributions of roach increases towards larger meshsizes, observed length distributions for perch positively skewed (meshsizes from 12 to 30 mm), most of observed length distributions for roach positively skewed, expected distributions for perch more in right than observed with meshsizes 12 and 35 mm, expected distributions for roach more in right than observed with meshsizes 12, 15, 25, and 35 mm, all expected length distributions higher than observed both for perch and roach.

Type of water: The sea area near Tvärminne zoological station, three different places, depths 2–5 m, 3–6 m and 6–14 m.

14

JENSEN, K.W. 1977: On the dynamics and exploitation of the population of brown trout, Salmo trutta, L., in Lake ∅vre Heimdalsvatn, Southern Norway.
Rep. Inst. Freshw. Res., Drottningholm, 56, 18 – 96. (Q)

Fishing gear: Set nets of monofilament, meshsizes 24, 26, 28, 30, 32, 36 mm (knot to knot). Dimensions 25,1 m × 1,41 m, 35,4 m².

Fishing conditions: Most of the catch was taken in August and the second half of September in a total of 87 nights in 1964–69. Nets used overnights only.

Species fished: Brown trout, Salmo trutta, L., material 1223 trout, length range 18 – 43 cm, girth range 87 – 223 mm. Food: Dominating food items cladocera, Gammarus lacustris, chironomidae. Behavior: Seasonal spawning migrations, rather stationary outside the spawning period.

Bycatch: None.

Selective effects: Model ratio girth/meshperimeter 1,21 (range 1,19 – 1,23). Modal length (1_m) can be computed from the meshsize by 1_m = 9,6 m. From the result a pilot fleet was constructed, 21, 21, 26, 29, 35, 39, 45, 52 mm, with a satisfactory equal selectivity curve in the range 20 – 45 cm.

Type of water: Oligotrophic mountain lake, surface area 0,775 km², max. depth 13 m, mean depth 4,7 m. Other fish species minnows Phoxinus phoxinus.

15

JENSEN, J.W. 1984: The selection of Salvelinus alpinus L. by bottom gillnets. Proc. 1st Int.Symp.Arct.Charr, Winnipeg 1981 (in press). (Q)

Fishing gear: Meshsizes 19.5, 22.5, 26, 29, 31, 39 and 45 mm (knot to knot). Dimension 25 × 1,5 m, 37,5 m². Setnets of nylon twine.

Fishing conditions: The nets were fished in the littoral zone on the reservoir bottom. Data from 1972 – 1980.

Species fished: Arctic charr Salvelinus alpinus L. Material: 2941 charr, length range 17 – 39 cm. Charr in the length intervall 17 – 28 cm had a mean condition factor of 1,15, larger charr 1,35.

Bycatch: No information

Selective effects: Computation of model length 1_m from the meshsize (knot to knot):

1 28 cm m = 0,017 × 1_m + 1,1

1 28 cm m = 0,120 × 1_m - 0,2.

A general selectivity curve was constructed and the efficency is given as a function of the ration 1/1_m. Combined selectivity of different pilot fleet is compared.

Type of water: The 27 km² Essand reservoir was impounded 6 m in 1948. The Nesjø reservoir is a complete impoundment of 39 km² from 1970. At water levels between altitudes 729 and 726 m the reservoirs have a common surface.

General remarks: Selectivity only secondary research object.

16

JOERGENSEN, H.S.: 1983 Miljoeundersoegelser for vandkraftprojekt Iterlaa Paamiut/ Frederikshaab 1983,
Available from: GROENLANDS FISKERIUNDERSOGELSER TAGENSUEJ 135, DK-2200 KOEBENHAVN N. In Danish. (N)

Title: Enviromental investigations of the water power project Iterlaa Paamiut/Frederikshaab 1983.

Fishing gear: Setnets from monofilament PA, each net made of 8 equal sections with the meshsizes 10–12.5–16–22–25–30–38–45 mm. Diameter monofilament 0.12 – 0.20 mm, total area of net 48 m² (or 8 mesh sizes with the area 6 m²).

Fishing conditions: 3 nets with a total length of 96 m (144 m²) were combined and set floating and at bottom at all depths. 4 lakes were investigated. The number of “net hours” (defined as one hour with a net 96 m long) varied between 61 and 187.

Species fished: Salvelinus alpinus (L.).

Bycatch: None.

Selective effects: Only a few data on this subject. Modal length of meshsize 16 mm is 20 cm. Fish size varied between 9 cm and 61 cm.

Type of water: Four lakes in Greenland. By definition oligotrophic, but with regards to Greenland eutrophic.

General remarks: Selectivity only secondary research object. Selectivity calculated using a combination of a skew-normal distribution and a normal distribution.

17

KÖLBING, A.: 1974 Der Starnberger See und die seinem Trophiezustand angemessene Bewirtschaftungsweise des Coregonenbestands. Veröff. Zool. Staatssammlung München 17, 1 – 108. (Lö)

Title: The Lake Starnberg and the management of its whitefish stock adapted to the tropic level.

Fishing gear: Setnets from monofilament PA, used as drifting- and bottom gillnets, meshsizes 35, 37, 40, 44, 48 mm.

Fishing conditions: Data from March 1971 to October 1971.

Species fished: Coregonus wartmanni C./macrophthalmus C./fera, indications on hybridisation during cultural eutrophication, age classes: I+ - III+, food: plancton.

Bycatch: None

Selective effects: Girth measurements to ascertain the appropriate meshsize.

Type of water: Subalpine lake southern Munich, Bavaria, undergoing cultural eutrophication. Surface area: 57.1 km², max. depth: 127 m, mean depth: 54 m. Exploitation of whitefish population by professional fishermen.

General remarks: Selectivity only minor research interest.

18

KÖLBING, A. 1975: Über Stellnetz-Maschenweiten in der Coregonenfischerei
Arch. Hydrobiol. 75, 3, 402 – 408, (D)

Title: On Meshsizes of Gillnets in Coregonides Fisheries

Fishing gear: Driftnets of PA monofilament, meshsize 40, 42 mm (length of one bar) meshsize determined by FLORIN meshgauge.

Fishing conditions: Time: July/August

Species fished: Coregonus lavaretus, girth range 16 – 20,2 mm with nets of 41,5 mm bar length.

Bycatch: none

Selective effects: Author denies the accepted rule that minimum meshsize bar length can be calculated from the division of minimum allowed fish length by 8. He gives evidence that the relation of girth to total length varies between 40 and 60%. The comparison with data from other lakes nearby reveals that these findings have only local importance and have to be reexamined in every new water.

Type of water: Data originate from

(surface area 57,1 km², depth/maximum 273 m) Starnberger See
(surface area 82,15 km², depth maximum 156 m), Chiemsee
(surface area 45,29 km², depth maximum 96 m) Ammersee

General remarks: Study aimed at better fish stock management by increase of legal meshsize.

19

KÖLBING, A. 1977: Über den Einfluβ erhöhter Netzmaschenweiten in der Coregonenfischerei
Arch.Hydrobiol. 80, 2, 239–247, (D)

Title: The effect of enlarged meshsizes in Coregonid Fisheries

Fishing gear: Driftnets of PA mono, diameter 0.15 mm, meshsize 40 and 44 mm (measured by FLORIN's meshgauge).

Fishing conditions: Nets set overnight over the deep parts of the lake, fishing season from 1st January to 15th October, fishing effort: one fisherman per 1,5 km² surface area, allowed effort 1500 netnights per year and fisherman, distribution of effort regulated by fishery plan set up by fishermens association. Effort considered to be inadequate.

Species fished: Coregonus lavaretus, AG II dominated catches of 40 mm nets, AG III those of 44 mm nets.

Selective effects: Enlargement of meshsize shifted average weight of fishes in the catches from 285g to 400g and increased catch per unit area.

Type of water: Deep supalpine lake Starnberger See, surface area: 57,1 km².

General remarks: Study undertaken for the evalution of a change in the legal minimum meshsize.

20

KORULCZYK, T. 1971: Efektywno poloww slepami.
Rocz. Nauk. Rol.,ser. H, t. 93, 4, 47–68. (SW)

Title: Effectiveness of fishing with trammel nets.

Fishing gear: Three-side nets.

Fishing conditions: Catches in lakes from October till December, and in lakes up to 100 ha also in July and August. Peak of the fishing effort in November in all lakes. Nets used in the lake littoral zone.

Species fished: Pike determined the level of catches. It constituted 36.7% of the catch on the average, and 55,7% in lakes bigger than 500 ha. The highest fishing yield of pike was observed in lakes 100 – 500 ha (57,4 kg/day). Overall average fishing yield of pike for all lake groups amounted to 4.03 kg/day of fishing with one net.

Bream: 19.6% in the catches. Overall fishing yield 2.15 kg/day. The highest percentage in the catch obtained in lakes up to 100 ha (33%), at fishing yield 4.32 kg/day.

Bycatch: Roach. 19.8% in the catches, at fishing yield 2.18 kg/day. Other species caught (tench, white bream and other) constituted altogether 23.9% of the catch, at fishing yield of 2.63 kg/day.

Selective effects: -

Type of water: Lakes divided into 3 size groups: I group: 0 – 100 ha, II group: 100 – 500 ha, III group: over 500 ha.

General remarks: Selectivity was not the main objective of studies. However, the study attempted to determine species selectivity of the gear. This selectivity amounted to 40.1% and 35.5% toward roach in August–September, and to 37% toward pike in autumn-winter period. Trammel nets are used to fish bigger specimens: pike BD (above 1 kg) amounted to 53%, pike S (0,5 – 1,0 kg) to 32%, bream DS (above 0,5 kg) to 95%.

21

KOSLOWSKA-FILAR, L. 1971: Efektywnosc potowow kozakami.
Rocz. Nauk Rol., ser. H, t. 93, 4, 69 – 86. (SW)

Title: Effectiveness of fishing with wing nets.

Fishing gear: Wing-nets, passive gear of the trap type, made of 3 or 4 hoops connected by wings and net leaders (fences). A typical wing-net has one main bigger trap (hoop net) and a few smaller side traps. In case of a “four-wing” net the front trap is the smallest one, and it is set at the shortest distance from the shore.

Fishing conditions: Wing-nets are used throughout the whole period when eel are caught, from the turn of March and April till the end of November. The highest eel catches are obtained in the second quarter of the year, when the intensity of wing-nets use is also the highest, about 90% in relation to the whole year.

Species fished: Eel constitutes 50.1% in all wing-net catches, the fishing yield being 1.23 kg/day of wing-net fishing. Pike: 13.4% and 0.33 kg/day. Roach: 13.3% and 0.33 kg/day.

Bycatch: Other species present in wing-net catches: bream, perch, tench, pike-perch, white bream, carp, at levels for each species not exceeding 6,5% of the total catch. Together these species constitute 23.2% of the catch, at fishing yield 0.56 kg/day.

Selective effects: -

Type of water: Intensity of exploitation, fishing yields and species selectivity in the following groups of lakes: I group: up to 100 ha in area, II group - 100 – 500 ha, III group - over 500 ha.

General remarks: Selectivity was not the main objective of studies. However, species selectivity of the gear was determined. Wing-nets are characterized by selectivity toward eel, especially from March till May. Selectivity toward pike in March – April in I and III group of lakes, and in April and October in II group. In the lakes in which wing-nets are used eel catches are 0.5 kg/ha higher on the average.

22

KRONBORG, O. 1984: PEDERSEN, H.V. & STOECKLER, M.: Redskabsselektivitet. In “En populationsdynamisk undersoegelse af helt, Coregonus lavaretus L., i Tange Soe” pp. 44–62. M.S. thesis University of Aarhus, Institute of Zoology. 306 pp., in Danish. (N)

Title: Selectivity of fishing gear.

Fishing gear: Setnets from monofilament nylon, meshsize 22.5–29–39–45–52–55 mm, area of nets 37.5 m², colour grey. Diameter monofilament 0.20 mm.

Seine nets with meshsizes 35 mm and 11 mm.

Fishing conditions: Data from August 27. 1982 to Nov. 30. 1983. Total catch of Coregonus lavaretus 3519.

Species fished: Coregonus lavaretus L., length range (fork) 17 – 48 cm, girth range 9.04 – 25.70 cm.

Bycatch: Salmo trutta lacustris, Salmo gairdneri, Coregonus albula, Osmerus eperlanus, Stizostedion lucioperca, Perca fluviatilis, Acerina cernua, Abramis brama, Blicca bjoerkna, Tinca tinca, Esox lucius, Anguilla anguilla, Alburnus alburnus, Lota lota, Rutilus rutilus.

Selective effects: Modal ratio girth/mesh perimeter 1.1, range 0.8 – 2.0 (nets).

L_1.0 = 30.0 cm, L_0.5 = 26.1 cm (35 mm seine net).

L_1.0 = 9.6 cm, L_0.5 = 8.3 cm (11 mm seine net).

Type of water: Man-made lake (made in 1921 by a damming of the river Gudenaa) with a total area of 5.75 km². Maximum depth 9 m, mean depth ab 2.5 m, mean retention time of water ab. 9 days and nights. Temperature range 0 – 20° C. Mainly exploited by fishermen (eel fishing), Coregonus not exploited.

General remarks: Selectivity calculated as part of a research program in the Lake Tange using McCombie & Fry's method and Gulland & Hardings method.

23

LAMPERT, W. 1971: Untersuchungen zur Biologie und Populationsdynamik der Coregonen im Schluchsee
Arch. Hydrobiol./Suppl. 38 (Falkau-Arbeiten 7), 3, 237–314 (D)

Title: Studies on the Biology and the Population Dynamics of the Coregonids in Lake Schluchsee

Fishing gear: Setnets from monofilament PA, meshsizes 20, 30, 35, 40, 45, 50, 55, 65 mm, diameter monofilament from 0,15 mm to 0,3 mm, area of nets 105, 95, 85, 75, 75, 75, 115, 125 m².

Fishing conditions: Data from May 1967 – July 1969, nets used mostly overnight, as driftnets with anchors hung up by floats in different depths over the deepest part of the lake, effort: 5 – 13 nets per night.

Species fished: Coregonus macrophthalmus C./fera, length range: 24 – 48 cm, weight range: 100 – 800 g, girth range: 160 –230 mm, food: mainly Cladocera, (Daphnia, Bosmina, Bythotrephes, Leptodora, Holopedium), behaviour: Daily migration between bottom layers and pelagic layers, main concentration in about 20 m depth during the night.

Bycatch: none

Selective effects: modal ratio girth/mesh perimeter 1.3, range 0,8 – 2,0, higher efficiency of net set towards bigger fishes.

Type of water: reservoir in Southern Black Forest, surface area 5,23 km², maximum depth 63 m, mean depth 21,8 m, exploitation only by sportfishermen.

General remarks: Selectivity only secondary research object.

24

LEOPOLD, M., NOWAK, W. 1964: Strukture gatunkowa potowow niewodem
Rocz. Nauk. Rol., ser. B, t. 83, 4, 645–654. (SW)

Title: Species yield of catches of winter seine with bags.

Fishing gear: Winter seine.

Fishing conditions: Catches since January till April.

Species fished: Roach (species determining the level of catches): 34.78% in the catches and 136.06 kg/fishing day. Catches of roach tended to increase (both in % and absolute values) along with increasing lake area. The highest level was obtained in lakes over 500 ha - more than 40% and about 200 kg/fishing day. Bream: 31.29% of the catch, and 122.41 kg/fishing day. The same levels in big and small lakes, while in medium lakes - 42%. Pike and perch were of importance in lakes up to 100 ha. Pike: 10.99% and 26.97 kg/fishing day; perch: 14.53% and 35.66 kg/fishing day.

White bream: Maximal catches in lakes 100 – 500 ha: 14.02% and 45.42 kg/fishing day.

Tench: in lakes up to 100 ha - 8% and 19.04 kg/fishing day.

Vendace: in lakes up to 100 ha and above 100 ha - 5% and respectively 16.87 and 26.28 kg/fishing day.

Bycatch: Species constituting less than 5% of the catch: whitefish, eel, pike-perch, crucian carp and other.

Selective effects: -

Type of water: Lakes of Mazurian Lakeland divided into 3 groups: up to 100 ha, 100 – 500 ha, and over 500 ha.

General remarks: Seasonal variations in species selectivity of the winter seine had different trends toward particular species in different classes of lake area.

25

LEOPOLD, M., NOWAK, W. 1964: Struktura gatunkowa polowow zakami.
Rocz. Nauk. Rol., ser. B, t. 83, 4, 655–665 (SW)

Title: Species composition of catches with fyke nets with rings.

Fishing gear: Fyke nets.

Fishing conditions: Materials from 101 lakes of Varmia and Mazuria. Period of catches 1951 – 1957. Catches since March till October each year.

Species fished: Species determining the level of catches: pike, tench, bream, and roach, totally 80% of the catch. There were periods when the fyke nets had very pronounced selectivity. And thus: toward pike in March (75%), April (56%) and October (60%); toward tench in July (41%), June (34%); toward roach in May (40%).

Bycatch: Less important species: perch - 6%, white bream - 5%, eel - 3%, crucian carp - 1%, pikeperch - 1%, other - 0.5%.

Selective effects: -

Type of water: Lakes of Varmia and Mazuria divided into 3 size groups: up to 100 ha, 100 – 500 ha, and over 500 ha, and into fishery types: vendace lakes, bream lakes, pikeperch lakes, tench and pike lakes, crucian carp lakes.

General remarks: Fyke nets in particular months had very pronounced species selectivity toward particular fish species. Depending on the fishery type of lakes different species were of importance in the catch:

-   in pike - tench and crucian carp lakes: pike and tench,

-   in bream and pikeperch lakes: pike and bream,

-   in vendace lakes: pike and roach.

26

LEOPOLD, M., NOWAK, W. 1964: Wybiorczosc mierozy.
Rocz. Nauk. Rol., Ser. B, t. 83, 4, 667–673 (SW)

Title: The species composition of trap net catches.

Fishing gear: Type II fyke nets (see Leopold M. et al EIFAC Tech. Pap. no 23, sup. 1, vol. II, 519–531).

Fishing conditions: Species selectivity and fishing yields were determined in lakes 0 – 1000 ha from March till September, and in lakes over 1000 ha from March till November.

Species fished: Species determining catches with type II fyke nets in lakes 0 – 1000 ha: pike - 36.99%, tench - 22.28%, bream - 15.19%, roach - 11.23%. In lakes over 1000 ha: pike - 45.43%, roach - 10.82%, bream - 23.98%, tench - 14.59%. Noticeable predomination of pike in all lakes (44.2% of the catch on the average). In lakes 0 – 1000 ha pike percentages in the catches were: in March - 100%, April - 78.92%, May - 31.10%, August - 60.93%. Tench was caught in July - 55.62%, and bream in May - 25.69%. In lakes over 1000 ha the respective percentages were: March - 87.58% of pike, April - 72.65% of pike, May - 64.82% of pike, October - 73.48% of pike, November - 79.18% of pike. Tench was caught in August (74.46%), and bream in June (45.89%).

Bycatch: Other species were rare in the catches, amounting only to 6.52%.

Selective effects: -

Type of water: Lakes.

General remarks: In some periods type II fyke nets are noticeably selective toward pike and tench, less so toward bream. Pike is caught in spring and autumn, tench and bream in summer.

27

LEOPOLD, M., Nowak, W. 1964: Wybiorczosc wontonow okoniowo-plociowych.
Rocz. Nauk Rol. ser. B, t. 83, 4, 675–680 (SW)

Title: The species composition of gillnet catches.

Fishing gear: Popular gillnets used all over Poland, made of steelon fabric, meshsizes 30 – 40 mm.

Fishing conditions: Data from 21 lakes with catches from April till December, and from Lake Mamry Poludniowe complex. The latter complex of lakes is very specific - the lakes are exploited with high fishing effort, and symptoms of a overfishing were observed. Catches in this complex in all months except February.

Species fished: Roach predominated in the catches in all months. In the complex of Lake Mamry Poludniowe roach catches varied from 51.6% and 0.90 kg/day till 90.1% and 2.79 kg/day. In other lakes roach catches ranged from 42.5% to 85.8%, and from 0.94 kg/fishing day to 4.51 kg/day. Perch was also caught. In Lake Mamry Poludniowe complex level of perch catches varied from 4.7% to 40.2%, and in other lakes from 2.6% to 43.7%.

Bycatch: Other species were treated together. Their total level never exceeded 22% of the total catch.

Selective effects: -

Type of water: Lakes

General remarks: High roach catches are obtained from April till July and in November and December.

28

LIBOSVARSKY, J. 1970: Survey carried out at Lac La Martre, Northwest Territories, in Summer 1969 and The entangling capacity of gill nets of different twine, color and age when fishing for whitefish and lake trout Fish. Res. Bd., Canada, Techn. Rep. 180, 1–36 (L)

Fishing gear: Three floating gillnets, undyed net 60 meshes deep, thread size 210/3, green net 20 meshes deep, blue net 30 meshes deep, thread size 210/6, meshsize 14 cm/stretched measure/length 91.4 m.

Fishing conditions: Data from experimental fishing August 1969, bottom setting, overnight, depths varying between 8 and 15 m, water transparency by Secchi 5–7m, effort: 3 nets for eight nights.

Species fished: Coregonus clupeaformis 416 ind., Salvelinus namaycush 145 ind.

Bycatch: Esox lucius 4 ind., Lota lota 1 ind.

Selective effects: The trial tested for differences in the numerical ratio of whitefish to lake trout/1/ and differences in the size composition in different nets /2/. Ad. 1 In seven settings out of the total of eight the nets yielded the same ratios of fishes. Ad. 2 The size distribution of whitefish caught in white net was different from both coloured nets. Very probably, it was the finer twine of the white net which caused the difference.

Type of water: Lac la Martre, Northwest Territories, Canada

General remarks:

29

LIBOSVÅRSK, J. 1976: Deriving the age structure of fish from gillnet catches Zool.listy 25, 3, 251–263 (L)

Fishing gear: Floating gillnets, monofilament and twisted nylon, meshsizes 3.8, 5.1, 6.3, 7.0, 7.6 cm /stretched measure/, 3.8 and 5.1 meshsize nets were 15.2 long, all others were 38 m long.

Fishing conditions: Data from October 1968 experimental fishing, bottom setting.

Species fished: Coregonus clupeaformis, length range 15–38 cm fork length, girth range 70–208 mm.

Bycatch: Not given

Selective effects: Three modal ratios were selected: 0.10 log G/P, 0.07 log G/P, skew normal model after Regier and Robson. /1966/

Type of water: Lake 302 lying in SW Ontario, Canada, area 23.7 ha, max. depth 13.8 m.

General remarks: The aim of the paper was to convert the size distribution generated by combining selection curves for each meshsize into the age structure.

30

LINDSTRÖM, T. 1961 Storleks- och artselektion hos nät och krokredskap.
Information från Sötvattenslaboratoriet, Drottningholm (1). 34 p. (In Swedish)

Title: Size and species selection by nets and hooks.

Fishing gear: Multifilament gillnets with meshsizes 25.0, 22.0 and 16.5 mm (knot to knot), flyfishing rod and longlining with ottertrawl.

Fishing conditions: Time period 1958–60.

Species fished: Trout and char.

Bycatch:

Selective effects: Fishes caught with ottertrawl and fly-fishing were tagged and released. The catch-curve for the net catches were then compared with the size distribution of tagged fishes.

Type of water: Four mountain lakes with trout and char.

General remarks:

31

LINLØKKEN, A. 1984: Garnseleksjon for abbor.
Fauna 37, 112–116 (Q)

Title: Gillnet selectivity for perch

Fishing gear: Set-nets of monofilament with diameter 0.15 – 0.17 mm. Meshes used 10, 12.5, 16.5, 22, 25, 30, 38 and 46 mm (knot to knot).

Fishing conditions: Data from May 1981 to May 1983. The nets are bottom set in the littoral zone and regularly lifted every day. The nets are linked together.

Species fished: Perch Perca fluviatilis. Material: 3061 perch. Length range 70 – 230 mm, Weight range 4 – 130 gr. No informations about food and behavior.

Bycatch: Brown trout Salmo trutta, arctic charr Salvelinus alpinus, whitefish Coregonus lavaretus.

Selective effects: The modal length (1_m) can be computed for different meshes (m): 1_m = 18,97 + 6,74 × m. According to this the ratio 1_m/m decreases with length. A general selectivity curve is constructed and the combined selectivity curve for different pilot fleet was estimated. The pilot fleet constructed by Jensen (1977) for unselective catch of brown trout will result in a skewed selectivity curve when used in a perch survey.

Type of water: Acidotrophic lake, 1.62 km², max. depth 31 m.

General remarks: Selectivity only secondary research object.

32

MISIK, V. 1966: Efektivnost tazby ryb ziabrovymi sietami v Oravskej nadrzi Pol'nohospodrstvo 12, 12, 910–920 (L)

Title: Effectiveness of netting fish by means of gillnets at the Orava basin

Fishing gear: Gillnets, twisted silon, meshsize, 4, 6 and 8 cm /bar measure/, length 30, 70 and 60 m, depth 4, 3 and 3 m. Monofilament gillnet, meshsize 4 cm, length 30 m, depth 3 m.

Fishing conditions: Data from 1960–1962, dates and type of setting not given.

Species fished: 1st net 13 fish species caught, 2nd net 8 species, 3rd net 8 species, 4th net 13 fish species, the frequency distribution differed from net to net.

Bycatch: see above

Selective effects: Not followed, the monofilament gillnet showed to be most effective: 42 ind./m²/200 days, 19.2 kg of fish/m²/200 days.

Type of water: Orava reservoir lying in the upper reach of Orava River, tributary to Váh River, N Slovakia. No further data given.

General remarks: Experimental fishing prior to launching commercional fishery.

33

MISIK, V. 1967: Selektivne posobenie exploatacnich prostredkov na druhovou skladbu ryb v nadrziach
Biologia/Bratislava/ 22, 6, 446–450 (L)

Title: Selective effect of fishing gears on species composition in reservoirs

Fishing gear: Gillnets, twisted silon, meshsize 4, 6, 8 cm/bar measure/. Monofilament gillnet, meshsize 4 cm. Beach seines: meshsize 4 cm, length 15 cm, depth 6 m, meshsize 1 cm, length 75 m, depth 8 m. Two fyke nets.

Fishing conditions: Not given

Species fished: In gillnets 13, 8, 7 and 13 fish species were caught. In beach seines 9 and 16 species and in fyke nets 7 and 8 species.

Bycatch: see above

Selective effects: Coefficient of selection was expressed by the formula k = c/a, c = number of fish species caught by the gear, a = number of fish species living in the water body.

Type of water: Orava reservoir, lying in the upper reach of Orava River, tributary to Váh River, N Slovakia.

General remarks:

34

MOLIN, G. 1958: Färg-Fisklighet. p. 114–118. Sv.Fisk.Tidskr. 67
(In Swedish.) (E)

Title: Colour-Catchability.

Fishing gear: 5 feet high gillnets of multifilament nylon with meshsizes from 27.3 to 46.2 mm (knot to knot) in the different colour (white, green, blue, brown, black and red).

Fishing conditions: During the ice free season. Between 55–112 net nights in each lake.

Species fished: The main catch consisted of whitefish, pike, perch, trout, roach, bream, depending on lake.

Bycatch:

Selective effects: The catch in % on nets with the different colours:

Type of water:

General remarks: All nets set on shallow water. Only the most frequently caught species are given in the table.

35

MOLIN, G. 1959: Färg-Fisklighet II. p. 77–80. Sv.Fisk.Tidskr. 68.
(In Swedish.) (E)

Title: Colour-Catchability II.

Fishing gear: 5 feet high gillnets of multifilament nylon with meshsizes from 27.3 to 50.0 mm (knot to knot, see Table), in the different colour (white, green, blue, brown, black and red).

Fishing conditions: During the ice free season. Between 13–106 net nights in each lake.

Species fished:

Bycatch:

Selective effects: The catch in % on the nets with the different colours:

Type of water:

General remarks: All nets set on shallow water. Only the most frequently caught species are given in the Table.

36

MOLIN, G. 1960: Färg.Fisklighet. p. 89–93. Sv.Fisk.Tidskr. 69
(In Swedish) (E)

Title: Colour-Catchability III.

Fishing gear: 5 feet high gillnets of multifilament nylon with meshsizes from 27.3 to 50.0 mm (knot to knot) in the different colour (white, green, blue, brown, black and red).

Fishing conditions: During the ice free season. Between 19–81 net nights in each lake.

Species fished:

Bycatch:

Selective effects: The catch in % on the nets with the different colours:

Type of water:

General remarks: All nets set on shallow water. Only the most frequently caught species are given in the Table.

37

MOLIN, G. 1961: Färg-Fisklighet IV. p. 58–62. Sv.Fisk.Tidskr. 70.
(In Swedish.) (E)

Title: Colour-Catchability IV.

Fishing gear: 5 feet high gillnets of multifilament nylon with meshsizes from 27.3 to 50.0 mm (knot to knot) in the different colour (white, green, blue, brown, black and red).

Fishing conditions: During the ice free season. Between 12–62 net nights in each lake.

Species fished:

Bycatch:

Selective effects: The catch in % on the nets with different colours:

Type of water:

General remarks: All nets set on shallow water. Only the frequently caught species are given in the Table.

38

NAGIEC, M. OSTROWSKI, P. 1973: Selektywnosc wontonow sandaczowych.
Rocz. Nauk Rol., ser. H, t. 95, 1, 83–99 (SW)

Title: Selectivity of gillnets for fishing pikeperch.

Fishing gear: Steelon gillnets, made of steelon fabric Td 210/3. Nominal meshsize of six nets: 40, 45, 55, 60 and 65 mm.

Fishing conditions: Data from 9 August till 18 September 1970, from Lake Wielimie, of pikeperch fishery type and area of 1790 ha. The nets were joint into sets of increasing meshsizes. They were set in the central part of the lake in four places. All nets, with the exception of those with meshsize 40 mm, were used for 10 days on each fishing ground. They were lifted up every morning. The gillnet with meshsize 40 mm was used for a few days less.

Species fished: Pikeperch measured up to 1 cm (lt and lc). The fish length ranges are given in the table below. Fish age: from 1+ to 7+. Description is given of the way pikeperch is stopped by the nets.

Statistical characteristics of the length distribution of pike-perch caught by gill-nets

Bycatch: none

Selective effects: Nets with depth of 30 meshes. Horizontal net setting coefficient = 0.56.

Type of water: Pikeperch lake, with pikeperch catches higher than the average for this type of lakes. Pikeperch in this lake is caught almost exclusively with set nets. Commercial yields of pikeperch increased systematically in 1960 – 1970 from 0.01 kg/ha to 6.40 kg/ha.

General remarks: Analysis of the selectivity of pikeperch gill nets. Estimation is given of the parameters of the selectivity curves.

39

NIELSEN, J. 1983: Fiskene i Skanderborg Soerne (118 pp).
Available from: Skanderborg kommune, Adelgade 44, DK-8660 Skanderborg. In Danish with English subtitles on figures. (N)

Title: The fish of the Lake Skanderborg.

Fishing gear: Setnets from monofilament PA, meshsizes 50–55–60–65–68 mm (measured from knot to knot), diameter monofilament 0.25 – 0.30 mm, area of nets 60 m². Colour green.

Fishing conditions: Data from April 1982 – December 1982. Nets used overnights mostly at bottom. Effort 20 – 50 nets per night, effort per net 200 nights.

Species fished: Abramis brama (L.), length range (fork) 18 – 41 cm, weight range 78 – 930 gr., girth range 14 – 32 cm, percentage of total catch 80% (in 50 mm) to 98% (in 68 mm).

Stizostedion lucioperca (L.), length range (fork) 18 – 75 cm, weight range 55 – 5000 gr., girth range 9 – 37 cm, percentage of total catch 5% (in 50 mm) to 1% (in 68 mm).

Bycatch: Perca fluviatilis L., Coregonus lavaretus L., Rutilus rutilus L., each species constituting 0 to 5% of the total catch.

Selective effects: Abramis brama, modal ratio girth/mesh perimeter 1.3, range 0.7 – 1.9.

Stizostedion lucioperca, modal ratio girth/mesh perimeter 2.2, range 1.6 – 2.9.

Type of water: Surface area 8.6 km², maximum depth 18.8 m, mean depth ab. 7 m., primary production in 1982 275 gC/m², temperature range 0 – 24°C. Sportfishing as well as commercial fishing.

General remarks: Selectivity calculated as part of a research program in the lake.

40

NILSSON, N-A. 1980: RAGNARSSON & N.G. STEFFNER: Ett försök med “krokvana” hos öring. Information frå Sötvattenslaboratoriet, Drottningholm (14), 12 p. (In Swedish)

Title: An experiment on trout with “hook-experience”.

Fishing gear: Spinning rod with ordinary sportfishing baits without barbs.

Fishing conditions: Reared 6 year old trout.

Species fished: Trout

Bycatch:

Selective effects: The fish, earlier not exposed to hook-fishing, rapidly became shy when exposed to intense sportfishing. Fishes caught earlier became even more difficult to catch.

Type of water: The experiment was conducted in four ponds (70 × 10 m)

General remarks:

41

NUMANN, W. und H. QUOSS 1971: Richtige Maschenweiten bei verschiedenen Garnstärken. Fischwirt 21, 77 – 82. (Lö)

Title: Right meshsize at different netting yarn sizes.

Fishing gear: drifting gillnet set, monofilament PA, diameter 0.15 mm; 0.12 mm.

Fishing conditions: Nets used overnight, at five different dates.

Species fished: Coregonus lavaretus wartmanni.

Bycatch: None mentioned

Selective effects: Higher efficiency of gillnets with identical meshsize but different fineness of the netting yarn (0.12/0.15).

Type of water: Lake Constance, F.R.G. Surface area: 476 km², max. depth: 252 m, mean depth: 100 m, exploitation mainly by professional fishermen.

General remarks: Critical examination of the method to determine the legal meshsize. The method - 5 meshes vertically and 10 meshes horizontally, stretched with 1 kg - gives correct results only at a yarn diameter of 0.15 mm. Theoretical considerations and measurements are supported by actual fishing results.

42

OLIVA, O., SOUKUP, V., FRANK, S., HOLCIK, J. and LOHNISKY, K. 1961: Ucinnost nekterych rybolovnych zarizeni Cs. rybarstvi 1961, 8, 118–119 (L)

Title: Effectiveness of some fishing gears.

Fishing gear: Gillnets mostly from cotton, meshsizes 14, 20, 22, 30, 40, 45, 60, 100 mm/bar measure/, colour brown and green, length of nets 5.5 to 13.6 m, depth of nets 1.3 to 2.9 m, nets with meshes 60 and 100 mm were 50 m long and 4 m deep. Beach seine, meshsize 10 mm, length 45 m, depth 4 m.

Fishing conditions: Data from 17 to 24 July 1954, nets were set at the surface, perpendiculary to shore line, fixed on the bank, anchored in water, catches obtained during night and day fishing were compared.

Species fished: 13 fish species were caught, most abundant were Rutilus rutilus, Abramis brama, Leuciscus cephalus, Perca fluviatilis, Blicca bjoerkna, Alburnus alburnus, 11 fish species were caught in beach seine.

Bycatch: see above

Selective effects: Not followed, different meshsizes yielded 0.2 to 2.0 fish/hour on the average, and 0.001 to 0.285 fish/hour/m² of net surface. Daytime effort by beach seine returned 76 g of fish/m² of net surface, night effort 574 g of fish/m² of net surface.

Type of water: Reservoir Slapy lying on Vltava/Moldau/River, exploitation by anglers.

General remarks: Experimental fishing prior to launching commercional fishery.

43

PARMANNE, R. 1972: Verkon silmävälin vaikutuksesta kalansaaliiseen meikäläisissä järvissä.
- Luk-tutkielma. Helsingin yliopisto, eläintieteen laitos. 57 pp. (S)

Title: The influence of the meshsize of the gillnet on the catch from Finnish lakes.

Fishing gear: Fleet of seven gillnets from twisted nylon, meshsizes 12, 17, 25, 35, 45, and 60 mm (bar length), length of each net 30 m and height 1.5 m.

Fishing conditions: Data from years 1961–1969, nets used overnight as bottom nets during open water.

Species fished: 22 species, most abundant in catch perch (Perca fluviatilis), roach (Rutilus rutilus), ruff (Acerina cernua), whitefish (Coregonus lavaretus) -1.); bream (Abramis brama), crucian carp (Carassius carassius), white bream (Blicca bjoerkna), pike (Esox lucius), vendace (Coregonus albula) and burbot (Lota lota).

Selective effects: The mean weights of trout, pike and burbot bigger in catch with meshsize 12 mm than in catch with meshsize 17 mm, mean weights of crucian carp of the same order of magnitude in catches with various nets, the mean weights of total catch per fishing unit 556.2, 985.3, 765,7, 454.8, 384.0 and 251.6 g (meshsizes 12, 17, 25, 35, 45 and 60 mm), respectively the mean numbers of fish in catch per fishing unit 37.7, 34.2, 8.7, 8.2, 0.8 and 0.3, the value (mk) of the catch biggest in eutrophic lakes and with meshsizes 35 and 45 mm.

Type of water: 49 lakes in different parts of Finland.

44

PIVNICKA, K., LISKA, L and JOHAL, M. S. 1984:
Direct estimates of gill net selectivity of roach/Rutilus rutilus L.
Prace VURH Vodnany 13, 50–67 (L)

Fishing gear: Gillnets knitted nylon fabric, meshsizes 28.1, 27.9, 28.6 and 39.7 mm/bar measure/, depth 2.5 to 3.6 m, length 30 m, twine thickness 0.167 to 0.240 mm. Haul seine, meshsize 8.3 mm, depth 2.75, length 2.75 m.

Fishing conditions: Data from middle to end of May 1977 to 1982. Haul seine only from 1980 to 1982.

Species fished: Rutilus rutilus, length range 14 to 25 cm.

Bycatch: Not given

Selective effects: By a direct comparison of gillnet and haul seine catches an average selection curve was given. The curve was unimodal/with modal length of 183 mm/and positively skewed.

Type of water: Klicava reservoir, surface area 68 ha, Central Bohemia, only experimental fishing allowed, no angling.

General remarks:

45

QVENILD, T. 1979: Utnyttelse av sik og ørret i Isteren.
Fiskerikonsulenten i Øst-Norge, rapport, 45 pp (Q)

Title: Exploitation of whitefish and brown trout in Lake Isteren.

Fishing gear: Set nets of monofilament with diameter 0.17–0.20 mm. Meshes 29, 35, 39, 45 and 52 mm (knot to knot). Beach seine of cotton with mesh 40 mm and nylon twine with mesh 26 mm. Longline baited with whitefish ( 17 cm) for the catch of trout.

Fishing conditions: Data from June, August and September/October in 1978–1980. The set nets are lifted every day. The beach seine fishery was carried out in the evening and night in June and August. The longline was operated in September/October.

Species fished: Whitefish Coregonus lavaretus and brown trout Salmo trutta. Whitefish: length range 25–45 cm, weight range 140–985 g. Brown trout: length range 35–75 cm, weight range 425–5300 g.

Bycatch: Perch Perca fluviatilis, burbot Lota lota, pike Esox lucius, grayling Thymallus thymallus.

Selective effects: For the beach seine the selection factor was 7,4 and the 1_c for 40 mm mesh was 32 cm. For the set nets the ratio for the modal length to the meshsize was decreasing from 10,7 for 29 mm mesh to 8,0 for 52 mm mesh as a result of the increasing condition factor with increasing size. The 1_c-value for longline was in the length range 50–54 cm.

Type of water: Oligotrophic lake, area 26 km², max. depth 32 m, mean depth 7,4 m. Active fishery with gillnets and beach seines.

General remarks: Selectivity study was carried out to evaluate the effect of change in meshsize of the gillnets.

46

QVENILD, T. & SKURDAL, J. 1981: Garnseleksjon for sik ved prøvefiske med flytegarn i Tyrifjorden.
Fauna 34, 110–115. (Q)

Title: Gillnet selectivity in whitefish surveys with pelagic gillnets in Lake Tyrifjorden.

Fishing gear: Pelagic gillnets of monofilament with diameter 0,17–0,20 mm, meshsizes (knot to knot) 21, 24, 26, 29, 35, 39 mm, area of nets 150 m² (25 × 6 m).

Fishing conditions: Data from June 1978 to October 1980. The catch from August and September is dominated by 2006 whitefish. The pelagic gillnets are regulated within the depth zone 2 – 46 m by mean of floats. The links are anchored in both ends. Effort: 1 series of 6 gillnets per night, nets are used only over night, total effort 372 gillnet nights located to four stations.

Species fished: Dominant species is whitefish Coregonus lavaretus with more than 90% of the catch in weight and number. Length range 22–33 cm, weight range 85 – 265 g, girth range 112–175 mm. Food: mainly cladocera (Daphnia galeata and Bosmina longispina dominating). Behaviour: Seasonal and diurnal migrations.

Bycatch: Brown trout Salmo trutta, perch Perca fluviatilis, smelt Osmerus eperlanus, arctic charr Salvelinus alpinus, pike Esox lucius.

Selective effects: Modal ratio girth/mesh perimeter 1,33. Combined gillnet selectivity showed that the gillnet fleet fished 27 cm with the highest efficiency, in the interval 24–33 cm the efficiency was higher than 78%. The selectivity curve is used to corrigate the length distribution.

Type of water: Oligotrophic lake, area 121 km², max. depth 295 m, mean depth 114 m, exploitation mostly by sport fishermen.

General remarks: Selectivity secondary research project.

47

QVENILD, T., SKURDAL, J. & DEHLI, E. 1982: Fangst og bestandsdynamikk for kreps i Steinsfjorden.
Tyrifjordutvalget, fagrapport nr. 16, 45 pp. (Q)

Title: Catch and population dynamics of crayfish in Lake Steinsfjorden.

Fishing gear: Traps with meshsizes 17,5 and 21 mm baited with whitefish or bream.

Fishing conditions: Data from 3. – 8. of August 1980 and 1981. Fifty baited traps were lifted for three consecutive mornings, the crayfish are marked and released. After the opening of the fishing season at 7th of August recaptures are registrated in the catches of the fishermen. The physical possibility for crayfish to escape through the meshes is evaluated in the laboratory.

Species fished: Crayfish Astacus astacus, material 5310 crayfish. Length range 72–110 mm, weight range 8–58 g. Food: detritus dominating. Behaviour: The size- and sex distribution will strongly affect the catch because of the agressive behaviour of crayfish. The molting cycle will also have influence on the catchability.

Bycatch: None.

Selective effects: The girth of the posterior part of the carapace is critical for escapement through the meshes. Selectivity curves for males and females are constructed for meshes 17.5 and 21 mm. The behaviour has influence on the curves. From the curves a twofold increase in survival of crayfish of less than legal size can be computed for the transformation from 17.5 mm meshes to 21 mm meshes in the fishery.

Type of water: Mesotropic lake, 13.9 km², max. depth 24 m, mean depth 10.2 m. Exploitation of crayfish 75–90% of the legal sized population (≥ 95 mm).

General remarks: Special study to evaluate the effects of new legislations.

48

STEINBERG, R.: Die Fängigkeit von Kiemennetzen für Barsch und Plötze in Abhängigkeit von den Eigenschaften des Netzmaterials, der Netzkonstruktion und der Reaktion der Fische.
Arch. Fischwiss. XII, 3, 173–230, 1962 (D)

Title: The catching efficiency of gillnets for perch and roach depending on the properties of the net material, the net construction and the reaction of the fishes.

Fishing gear: bottom set gillnets, meshsize (bar length) 33, 34, 36, 43 and 50 mm, material: PA mono, diameter 0,20 mm (33 and 34 mm meshsize) and 0,25 mm (36, 43 and 50 mm meshsize).

Fishing conditions: nets sets overnight from April to November 1958.

Species fished: Perca fluviatilis 32 – 50 cm total length, Rutilus rutilus 33 – 50 cm total length; average weight perch 211 g (36 mm), 365 g (43 mm), 623 g (50 mm), average weight roach 191 g (36 mm), 333 g (43 mm), 471 g (50 mm).

Selective effects: Average total length of perch and roach depends on bar length according to the formulas LT = 0,4519 BL + 9,44 (perch) and LT = 0,54 BL + 5,5 (roach).

Type of water: Lake of Ratzeburg, surface area 16 km², eutrophicated post-glacial lake, visibility 2,0 – 3,5 m Secchidisc, thermocline in 9 m depth during summer, hypolimnion devoid of oxygen during that season; lake is exploited by a professional fishermens association and sportfisherman.

General remarks: mesh selectivity only secondary object of the study.

49

SWIERZOWSKA, L., DEMBINSKI, W. 1978: Proba oceny efektywnosci polowow elektrycznymi agregatami i tukami elektrycznymi.
Rocz. Nauk Ro., ser. H, t. 98, 4, 129 – 146. (SW)

Title: A trial at estimating effectiveness of catches by means of electric assemblies and eel pair net.

Fishing gear: Electric fishing gear (aggregate - convertor). Classical electric fishing with constant current, at a depth not exceeding 2 m. Electrified eel pair net working on the basis of an electric aggregate and a transformer. Catches in lake centre (open water) at different depths.

Fishing conditions: Electric aggregate - data from 33 lakes for the period 1968 – 1975 (total area of lakes 22060 ha). Totally 2056 hours of fishing. Effective daily catch - 5 hours on the average. Catches from April till December. Electrified eel pair net: data for the period 1967 – 1975 from 28 lakes (total area of the lakes 24920 ha). Average fishing time - 6 hours daily. Totally 3028 hours of fishing. Intensiveness of lake exploitation with the pair net was not high, amounting to 1.6 units of effort/ha on the average. Catches from June till November.

Species fished: Electric aggregate: -eel 51% of total catches and 86% of their value. Spring catches most effective - 75% of eel, in summer 42% of eel, in autumn 14%. In autumn high percentage of pike - 32%, and 19% of pike in total catches. Tench - 6.1% in total catches, carp - 4.0%, roach - 10.3%, white bream - 2.6%. Electrified eel pair net; -eel 75% in lakes up to 100 ha, 47% in lakes 100 – 500 ha and 45% in lakes over 500 ha. The highest eel yields in lakes up to 100 ha: 43 kg/fishing day.

Bycatch: Electric aggregate: bycatch of various species constituting less than 3% in total catches. Overall percentage of these species: 7.5% in total catch.

Eel pair net: bycatch divided into two groups. I group (bream, perch, pike) - 28% of the total catch, similar percentages of particular species. II group (pikeperch, tench, roach and white bream) - 26% of total catch. These species occurred at different but low percentages in the catch.

Selective effort: -

Type of water: -

General remarks: Selectivity was not the main objective of studies. High species selectivity of the gear observed in course of the studies should be, however, pointed out. Both gears are considered do be eel fishing gear. Average share of eel: 51% in electric aggregate catches, 45% in eel pair net catches.

50

SWIERZOWSKI, A., DEMBINSKI, W. 1978: Selektywnosc przestawy wegorzowej i struktura wielkosci wegorza sptywajacego z jeziora Sasek Wielki.
Rosz. Nauk Rol, ser. H, t. 98, 4, 147–157

Title: Selectivity of an eel trap net and size structure of eel run from Lake Sasek Wielki. (SW)

Fishing gear: Two-chamber framed eel trap made of steelon net. Bag no 1: steelon fabric Td 210/15, meshsize 23.8 mm. Bag no 2: steelon fabric Td 210/15, meshsize 19.9 mm. Cover: steelon fabric Td 210/12, meshsize 10.2 mm.

Fishing conditions: May 1970. Traps used at night, since sunset till midnight, at an outflow from Lake Sasek Wielki, at a distance of 150 m from the lake. Lake area 870 ha, average depth 8.2 m, maximal depth 38.0 m. Water flow in the outflow 1 m/sec.

Species fished: Eel in 22 length (lt) classes, within the range 33 – 99 cm. Dependence was calculated between eel weight and length.

Bycatch: None

Selective effort: Particular net bags were set on rings 0.6 m in diameter, coefficient of net setting u = 0.67.

Type of water: Outflow from lake. Water flow 1 m/sec.

General remarks: Selectivity factors for the bag tested amounted to SF = 23.5 and 25.3.

51

SZCZERBOWSKI, J. 1977: Selektyywnosc wontonow oraz szrost i przezywalnosc sieji w jeziorze Mamry.
Rocz. Nauk Rol., ser. H, t. 98, 2, 135–148 (SW)

Title: Selectivity of gillnets and growth and survival of lake whitefish in Lake Mamry.

Fishing gear: Sets of gillnets consisting of 7 nets, meshsizes: 40, 45, 50, 55, 60, 65 and 70 mm. Net fabric of steelon cord no 30. Top line: twined steelon cord with floats of polocel. Bottom line: loaded cord. Net dimentions: 45 × 5 m.

Fishing conditions: Catches July – August in 1972 and 1973, in Lake Mamry Polnocne, at a depth of about 20 m.

Species fished: Whitefish of body length range 21 – 51 cm. Along with increasing meshsize average length of the fishes caught increased. Dependence was calculated between fish age and weight. Survival was assessed at 32%.

Bycatch: None

Selective effects:-

Type of water: Lake Mamry Polnocne.

General remarks: The paper gives rough and approximate results on the selectivity of gillnets.

52

VOSTRADOVSKA, M., VOSTRADOVSKY, J. 1962: Hospodarska tesba ryb na udolni nadrzi Lipno z hlediska ucinnosti nekterych odlovnych zpusobu. PRACE VURH Vodnany no.2 : 85 – 115 (V)

Title: The commercial fishing in the Lipno reservoir and the selectivity effect of the different fishing methods.

Fishing gear: Monofilament floating gillnets 30, 50, 100 mm bar meshsizes, 30 – 50 m in total length and 2.5 m heigh. Fyke nets in different body size with 10 mm, 20 mm and 30 mm bar lengths. Seine net with 10 – 20 mm meshsizes and bottom longline-fishing.

Fishing conditions: Reservoir in the first period after filling with water, intensive angling (carp and pike), commercial fishing by gillnets, seine nets mainly (roach, bream, pike, carp, perch, tench) in summer time only (during 6.00 p.m. and 7.00 a.m.).

Species fished: Roach - 21.20% (Rutilus rutilus) pike - 19.75% (Esox lucius), bream - 15.53% (Abramis brama), carp - 13.44% (Cyprinus carpio), tench - 11.41% (Tinca tinca), perch - 10.05% (Perca fluviatilis), burbot - 5.38% (Lota lota), eel - 0.69% (Anguilla anguilla).

Bycatch: chub (Leuciscus cephalus), bleak (Alburbus alburnus), silver bream (Blicca bjoerkna), rudd (Scardinius erythropthalmus), crucian carp (Carassius carassius).

Selective effects: The effective selective characteristics were ascertained in the gillnets of 50 mm (pike and roach) and 30 mm meshes (roach and bream). Roach from 50 mm meshes are more than 96% between 251 –300 mm body length, from 30 mm meshes between 201 and 250 mm. Into the gillnets of 30 mm meshes still the annual sets of fish hatched in the dam period were caught. In the seine net catches, bream and roach of 100 til 200 mm were prevalent. Longline fishing was selective on eels and burbot only. Burbot in gillnets 50 mm were in 451 – 500 mm body length only and with longline fishing in 201 – 700 mm.

Type of water: Man-made lake 4650 ha in Southern Bohemia, average depth 6 m, bottom with many shrubs, stumps, stones. More than 1000 ha of peat-boges with small floating turf islands. Water browny coloured, lower transparency whole year.

53

VOSTRADOVSKA, M., VOSTRADOVSKY, J. 1982: On the speed of Repopulation of Poisoned Lagoons and Possibility of Net Fishing in Cuban Freshwaters.
PRACE VURH Vodnany, 11: 159–168 (V)

Title: See above

Fishing gear: Floating multifilament silon gillnets with 30 mm bar meshsize, 30 m in length and 1.8 m high, in white, black, red, green and grey colours. All gillnets were in the same size, only colours were different. Seine net was made from seven thread, 0.50 thick, length 40 m, 2.2 m high. Central part e.g. 20 m was 10 mm, margins 15 mm. Fykes were with central wings, length 2 m, max. high 0.6 m, meshsize 10 mm.

Fishing conditions: Data from 1967 of smaller Cuban lagoons from gillnetting and trapping. Seining were made only in Mosquito and Cacoyugüin reservoirs. Conditions are influenced by a great quantity of flooded shrubs in lagoons and infestation with algae in reservoirs. Depth 1–6 m, transparency between 0.3 and 3m.

Species fished: Cichlasoma tetracantha (44 – 58% in averages), Lepomis macrochirus (16 – 46% in averages), Micropterus salmoides (10 – 26% in averages).

Bycatch: Poecilia vittata 30 % in seine net.

Selective effects: Gillnets 30 mm and seine net 15 - 10 - 15 mm were more effective gears than fyke nets. Average size of fish in gillnets and seine net were: Chichlasoma tetracantha 133 mm and Lepomis macrochirus 123 mm of body length in lagoons. The size selective effect was smaller due to body shape and influence of spiny fin. The gillnets captured mostly fish between 141 – 180 mm in reservoirs. The night time was most effective time for fishing. Dark coloured gillnets as black, red, green were more effective in waters with higher transparency, ligtly colored nets as white and grey were more effective where the transparency of water was lower. Small effect of application of fyke nets were due to capture a large quantity of freshwater tortoises which quickly died and decayed. Only in Mosquito reservoir fyke nets were effective by the catch of Anguilla rostrata, 750–950 mm of total length.

Type of water: Both lagoons Sabanilla and La Luisa, reservoirs Mosquito and Cacoyugüin are influenced with water level fluctuation (lower during dry season). Surface area from 1.5 ha up to 40 ha, mean depth 1.5 – 6.0 m. Vegetation adds difficulty to the fishing.

54

VOSTRADOVSKY, J., LEONTOVYC, I., VOSTRADOVSKA, M. 1974: K vyvoji rybarskych pomeru ve vodarenske udolni nadrzi Svihov (Zelivka) s posouzenim lovneho ucinku tenat, zatahove sete a elektrickeho agregatu.
BULETIN VURH Vodnany, 2: 25 – 36 (V)

Title: On the development of the Fishery Conditions in the Reservoir Svihov (Zelivka), and the evaluation of the Fishing Effect of Gillnets, Dragnets and Electro-Fishing Gear.

Fishing gear: Monofilament floating gillnets with the 30, 50, 60, 80 bar meshsize, 2.5 m depth, 30 – 50 m length. Drag net 20-8-20 mm meshsize, 40 m length, 4 m depth, el. apparatus 500 V and 1.5 – 2.0 A.

Fishing conditions: 25 fish species were present. Pikeperch, pike, silver carp, big head are stocked artificially. Angling not allowed. Storage reservoir for drinking water.

Species fished: Roach (Rutilus rutilus), pike (Esox lucius), pikeperch (Stizostedion lucioperca), rapacious carp (Aspius aspius) mainly. Bream (Abramis brama), chub (Leuciscus cephalus), tench (Tinca tinca), barb (Barbus barbus), white bream (Blicca bjoerkna) less.

Bycatch:

Selective effects: Gillnets with the 30 mm mesh capture non-predatory fishes, perch and roach, mainly. The gillnets mesh 50, 60, 80 mm captured predatory fish mostly pike, pikeperch, rapacious carp (92 – 95 % of the total catch). Non-predatory fish species are fished when seines were used in night in the shore (roach 45 – 91 %, bream 6 – 47 %). The electric apparatus were effective only in the period when fish gathered in shallow and near the influence, mainly in the spring season (roach 66 %, pike 10 %).

Type of water: Man made lake 1500 ha. Drinking water storage reservoir. Max. depth 40 m. Gillnets were used during overnight as surface nets, seine hauling mostly in the evening and in the night, depth in the place of seining 1 – 6 m, gillnets and seine nets were used in the same area of reservoir. Electrical gear in shoreline and in inflow.

55

WOHLGEMUTH, E. 1979: On selectivity of gillnets for, and certain biological parameters of Alburnus alburnus and Rutilus rutilus.
Folia zool., Brno, 28/4/: 371–383. (L)

Fishing gear: Experimental fleet of gillnets, meshsizes 9, 15, 22, 30, 37 and 45 mm/bar measure/, all twisted nylon, the first three nets were 25 m long, their denier was 120/2/3, further three nets were 50 m long, their denier was 120/4/3.

Fishing conditions: Data from 20 and 21 Oct. 1971, weather cloudy, W wind, and from 5 to 8 June 1972, weather fair, sunny, W or SW wind, on 7 June, in the eve ning a heavy rainfall followed by a spell of misty and calm weather. Nets were set overnight for 12 to 14 hours, parallel with banks. Effort: all nets per night.

Species fished: 8 fish species captured, most abundant were: Alburnus alburnus, 221 ind., total length range 95 to 235 mm, girth at mesh mark 31 to 110 mm, weight 25 to 110 g; Rutilus rutilus, 74 ind. caught, length range 165 to 245 mm, girth at mesh mark 83 to 131 mm, weight 50 to 180 g.

Bycatch: Aspius aspius 6 ind., Stizostedion lucioperca 3, Abramis brama 3, Perca fluviatilis 2, Blicca bjoerkna 1, Scardinius erythrophthalmus 1.

Selective effects: R. rutilus modal ratio girth at mesh mark/mesh perimeter, 1.16; A. alburnus, 1.2.

Type of water: River reservoir on Svratka River near Brno water surface 250 ha, depth at fishing site 4 m, exploitation by anglers only.

General remarks: Selectivity presents one part of the research object.