by
Juan Rodolfo Serra
Undersecretariat of Fisheries
Teatinos 120, Piso 11, Of. 44
Santiago, Chile
Resumen
Se presentan los antecedentes generales sobre la pesquería pelágica Chilena, en relación a su ubicación, extensión geográfica y características oceanográficas, distinguiéndose las unidades de pesquerías que la componen, a saber la de la zona Norte (límite con Perú hasta 25°S), Coquimbo (29°-30°15'S) y Talcahuano (36°10'- 37°10'S).
Con la información de las estadísticas de captura, flota y esfuerzo pesquero, expresado como viaje estándar con pesca, se documenta la historia de las dos unidades de pesquerías más importantes, que son Zona Norte y Talcahuano. Se destaca el origen de ambas pesquerías, que ocurrió a principios de la década sesenta y que obedeció a una política de fomento pesquero. Esta produjo un desarrollo explosivo inicial que provoco una gran sobreinversión en la industria pesquera.
El análisis de la distribución geográfica y estructura poblacional de la anchoveta (Engraulis ringens), caballa (Scomber japonicus peruanus) jurel (Trachurus murphyi), sardina común (Clupea (Strangomera) bentincki) y sardina española (Sardinops sagax) permite concluir sobre las variaciones ocurridas en la distribución de estas especies, siendo quizás la más espectacular la observada en sardina española, especie que colonizó todo su ambiente, definido por el sis- tema Humboldt, produciéndose incluso nuevas áreas de desove; por otra parte es dramática la reducción observada en las áreas de desove de la anchoveta.
Las cinco especies analizadas presentan patrones de historia natural similares. Todas son iteróparas y los parámetros de longevidad, crecimiento y primera madurez conforman un patrón consistente, concordante con lo establecido por Beverton (1963). Presentan si diferencias en los patrones geográficos de desove, principalmente entre los clupeoídeos (anchoveta y sardina española) y el jurel. Los primeros se concentran para desovar formando áreas definidas y densas de desove; los segundos en cambio se dispersan distribuyendo los produc- tos reproductivos en grandes áreas de desove. La anchoveta y sardina española desovan en áreas de mayor estabilidad de acuerdo con los conceptos de Lasker (1981) en cambio el jurel desova en áreas de gran transporte de Ekman y alta turbulencia.
Junto con los cambios en la distribución geográfica se observan fuertes cambios en la abundancia de las especies. Los recursos de anchoveta (Zona Norte) y anchoveta-sardina común (Talcahuano) disminuyen su abundancia colapsando en 1977 y 1976 respectivamente. Por otra parte se observa el crecimiento de la abundancia de la caballa, jurel y sardina española, el que se inicia a principios de la década del setenta. El cambio más espectacular de la abundancia ocurre con la sardina española, cuyas capturas crecen desde el nivel de 10. 000 ton. en la década sesenta a 1 600 000 toneladas en los últimos años. La segunda especie en importancia es ahora el jurel, cuyas capturas crecen en la zona norte desde 15 000 toneladas en la década sesenta hasta 435 000 ton. en 1981 y en Talcahuano desde menos de 5 000 ton. hasta 400 000 ton. en 1980.
En la pesquería Zona Norte el sistema derivó del dominio de la anchoveta al de la sardina española y en Talcahuano del dominio del recurso mixto ancho- veta-sardina común al del jurel. Estas pesquerías bien podrían ser definidas como sucesionales.
El cambio de la especie dominante en ambas pesquerías, significó que las capturas totales aumentarán a más del doble.
Los niveles de explotación alcanzados en la explotación de la anchoveta (Zona Norte) y anchoveta-sardina común (Talcahuano) fueron demasiado altos de acuerdo con el conocimiento actual disponible sobre recursos pelágicos, de donde resulta cuestionable culpar sólo a los factores ambientales del colapso de estos recursos.
Es sorprendente constatar que estos recursos cuando se encuentran en la fase de crecimiento explosivo como la experimentada por la sardina española, puedan soportar tasas de explotación extraordinariamente alta (70%) sin demostrar haber sido afectadas negativamente.
La historia de estas pesquerías parece indicar que la combinación tasa de explotación alta junto con condiciones ambientales adversas es muy peligrosa para la permanencia de niveles de abundancia adecuados para la actividad pesquera.
INTRODUCTION
Pelagic fisheries in Chile are located between the border with Peru and 37° 10' S in the highly productive system of the Humboldt current. It is the most important fishing activity in Chile and represents around 80% of the landings of marine products. Fish meal and oil exports represent a figure close to 250 million dollars, and constitute the third most important export products of the country.
The following three fishery units exist in this area:
- Northern Zone: from the border with peru to 25°S.
- Coquimbo: 29° 00' - 30° 15' S.
- Talcahuano: 36° 10' - 37° 10' S.
The species supporting these fisheries are mainly the following: anchovy (Engraulis ringens), mackerel (Scomber japonicus peruanus), jack mackerel (Trachurus murphyi) common sardine (Clupea (Strangomera) bentincki) and spanish sardine (Sardinops sagax). With the exception of common sardine, which only appears in Talcahuano, the remaining species are present in greater or lesser proportion in the three fisheries units at present, which was not always the case.
This paper deals mainly with the Northern Zone fisheries, which began in 1957 in Africa on the basis of anchovy, and with the Talcahuano fishery, which began in 1965, when transformation of the fleet was started. This activity was developed on the basis of mixed common sardine and anchovy resources, which are captured together in varying proportions.
The development of these fisheries, and mainly the Northern Zone fisheries, were the result of development policies in which stock abundance was not properly considered and led to great over-investment. Both fisheries collapsed causing the idleness of a considerable part of the industrial capacity, which subsequently was fully used as a result of a substantial increase of catches due to an impressive growth of spanish sardine and jack mackerel stocks, which were caught in insignificant quantities in the sixties.
The purpose of this paper is to describe these fisheries and the changes they have undergone.
Fig. 1. Geographical location of the chilean pelagic fisheries.
HISTORY OF THE FISHERIES
Catches
Northern Zone Fisheries Unit. Figure 2 shows catches of anchovy, spanish sardine, jack mackerel, mackerel and their total, obtained between 1961 and 1981 in the northern zone. The changes in the stocks of these species are clearly reflected by the catches, the most important being the collapse of anchovy (1977) and the change, between 1973 and 1977, from practically monospecific to multispecific fisheries, mainly because of the increase of spanish sardine, jack mackerel and secondarily of mackerel.
Between 1964 and 1971 anchovy went through a "plateau" of high instability; it dropped to a new level in 1972 and collapsed in 1977. Since then it has shown marked fluctuations around the level of 100,000 tons.
Spanish sardine became the dominant species in 1977, surpassing the remaining three in 1979 by a large margin and reaching a peak in 1980 with a record catch of 1,592,000 tons. In 1981 it dropped to 1,425,000 tons.
From 1978 on jack mackerel, with 365,000 tons, became the second species in importance; it decreased in 1979 and 1980, and increased substantially in 1981 reaching a level of 435,000 tons.
Finally, mackerel catches which reached a maximum of 171,000 tons in 1978 after sustained growth, insinuate a decrease, although their behaviour is somewhat erratic.
It is important to stress the level of total catches of fisheries in the Northern Zone in the years when anchovy and spanish sardine were dominant (1967-1971). The level reached since 1979, with spanish sardine as the main species, more than doubles the level reached in the sixties with anchovy.
Talcahuano Fisheries Unit. In this unit fisheries was developed on the basis of the mixed resource of anchovy and common sardine. As in the Northern Zone, it underwent great changes in the composition as regards species and in its catches (Fig. 3).
The mixed anchovy and common sardine resource underwent great fluctuations between 1967 and 1974, and decreased drastically from 164,000 tons caught in 1974 to 47,000 tons in 1975 and then it collapsed in 1966, when 6,600 tons were caught.
As the mixed anchovy and common sardine resource collapsed, jack mackerel catches began to grow showing sustained increases until 1981 with a peak of 406,000 tons.
Spanish sardine began to be caught in this area in 1973. This species was entirely unknown to the fishermen in this zone. Catches increased significantly between 1979 and 1981, reaching a level of 80,000 tons.
In Talcahuano the system passed from the domination of anchovy and common sardine to that of jack mackerel with spanish sardine in second place. The latter species was previously unknown in this latitude. In the Northern Zone this order is reversed spanish sardine being the dominant species.
As in the North, the change in the composition of species and, maybe more app appropriately, the replacement of the dominant species in the system, is the reason for present yields to be more than double than in the previous system in which anchovy and common sardine were dominant.
Fleet and Fisheries Effort
Northern Zone Fisheries Unit. The fleet in this area is composed of boats of the Pacific coast Seiner type. It went through a period of accelerated growth between 1962 and 1965, from less than 50 to 251 units, which is the maximum number reached in these fisheries. Later it decreased to 100 units in 1974. Good fishing conditions from 1975 onwards stimulated a new expansion of the fleet which increased to 158 boats in 1981. (Fig. 4) (Serra, in press, Martinez et al. 1981, 1982).
Fig. 2. Total catch, by species, taken in the Chilean northern pelagic fishery (1961- 1981).
Fig. 3. Industrial
catches of anchovy-common
sardine(-)
jackmackerel (---) and
spanish sardine (+++)
of the Tacahuano
fishery.
(Data Source: IFOP)
Fig. 4. Evolution of the fleet of the Chilean northern pelagic
fishery (1958-1981). A. number of boats B. Boat size,
expressed as mean hold capacity.
From Serra 9in press)
The seiner fleet in the Northern Zone is composed of three small fleets, which operate out of the most important ports, i.e., Arica, Iquique and Antofagasta (including Mejillones). The greatest changes take place in the fleet operating out of Iquique which generally takes the lead in changes introduced in the fleet of these fisheries.
The increase in size of the boats is expressed by average fish hold capacity measured in cubic meters. Figure 4 also shows the evolution of the size of the boats of Arica, Iquique and Antofagasta (including Mejillones). The increase of the average capacity of the fish hold is the result of the incorporation of larger fishing units, withdrawal of the older and smaller units, transfer to other ports and also to other fisheries, such as Talcahuano, for example (Serra, 1978). It may also be observed that most of the renewals of the fleet are made in Iquique, where the curve continued to increase after 1970; on the other hand, it becomes stabilized in the other ports. In recent years, 1980-1981, the average fish hold capacity reached levels of 250 cubic meters.
Serra (in press) states that together with the historical growth of the fleet there is a gradual improvement in fishing gear, such as the incorporation of the power block, absorbent pumps, acoustic equipment, larger nets, airplanes for surveying activities and collaboration in fishing operations. Later, in 1978, other changes were made such as the replacement of the 13 mm mesh size anchovy net by a 38 mm mesh size sardine net. The replacement of practically all the nets was completed by the end of 1979. Neverheless, when large concentrations of anchovy are detected the sardine nets are exchanged for anchovy nets. This process takes place mainly in Arica.
The fleet of the Northern Zone operated only in daytime up to 1974, when nighttime fisheries were stated and gradually increased; in 1978 they were intensified through the incorporation of airplanes for nighttime aerial surveys.
Due to the difficulty of obtaining data regarding the time spent in searches, which in addition is very difficult to measure because of the "airplane effect", the fishing effort is measured by the number of trips. Two units are used: total standard trips and standard trips with catch. The total number of trips is obtained by adding the fishing and non-fishing trips. The criterion used to estimate the effort per species is to assign fishing trips to the dominant species of the catch, to which non-fishing trips are added when measured as total number of trips. The effort is standardized with respect to the size of the boats, using the 130 to 179 cubic meters fish hold as the standard size.
Figure 5 shows total catches and the gross effort expressed as the total number of trips for all species. If it is considered that the total catch is a measure of the stocks (r=0.67; 20 d.f). Another important conclusion is that notwithstanding the lower number of fishing units existing at the end of the seventies and beginning of the eighties, with respect to the maximum of the sixties (Fig. 4), the total number of trips for all species was similar. This proves the great efficiency achieved by the industrial seiner fleet.
Fig. 5. Total catch and gross effort in the Northern Zone fishery. Captura= catch; esfuerzo (TV) = effort.
Figure 6 shows the history of anchovy fisheries and the explosive development of the fishing effort measured by the total number of standard trips.
Talcahuano fisheries unit. As in the Northern Zone the fleet in this area is composed of seiners of the Pacific Coast Seiner type. It totalled a maximum of 48 boats in 1969 (Fig. 7), declined until 1972, after which it increased and became stabilized between 1974 and 1976 at an intermediate level of 37 to 39 boats. (Serra, 1978). Subsequently, it continued to increase until it reached a total of 56 boats in 1981 (Martínez, Bohm and Salazar, 1982).
In 1965 the average size of a boat, measured by the capacity of the fish hold, was of approximately 50 cubic meters; it grew rapidly until 1970 reaching a level of 120 cubic meters; it remained relatively stable in the following years and underwent a new phase of growth in recent years, reaching 152 cubic meters (Fig. 7).
Fig. 6. Catch, effort and cpue of the Chilean anchovy
fishery of the northern zone. 1961 - 1977.
From Serra (in press)
Serra (1978) discussed the transformation that took place in the Talcahuano fleet, where the new boats incorporated, mainly in the development phase of these fisheries (1965-1969) were better equipped with acoustic equipment, power blocks, absorbent pumps and larger nets. The original anchovy nets were replaced in 1969 by jack mackerel nets, with a mesh size of 50 mm. Nighttime fishing is another innovation that was introduced 1979, fundamentally to catch spanish sardine.
Fig. 7. Evolution of the fleet of the Talcahuano fishery (1965-1981).
A: number of boats. B: boatsize expressed as mean hold
capacity.
From Serra (1978) actualized with data from Martínez, Bohm
and Salazar (1982).
Figure 8 shows the development of the fishing efforts for anchovy and common sardine, which grew considerably in the initial phase and declined after having reached the maximum level of 6,351 standard trips in 1970. The present level is shown in Figure 9 and refers to the effort applied to jack mackerel fisheries and is expressed as total standard trips and standard trips with catch, as in the case of the Northern Zone fisheries.
Fig. 8. Fishing effort on the anchovy-common sardine fishery of
Talcahuano, expressed as standard trips refered to the
140-149 m3 hold capacity boat size.
From Serra (1978). Esfuerzo=effort; años=years
Fig. 9. Catch, effort and cpue of the jack mackerel from the Talchauano fishery. From Serra and Zuleta (1982) TVE: total standard trips; VCPE: standard trips with catch.
OCEANOGRAPHIC FEATURES
This zone corresponds to the eastern border of the anticyclonic gyre of the Southern Pacific, whose southern boundary is the drift of the western wind, which hits the Chilean coast at approximately 43° latitude south, originating the Humboldt System. The latter is basically formed by three permanent currents and by a complex system of occasional flows and counterflows.
The zone has been typified as one of "eastern border currents", with slow and wide flows in the direction of Ecuador, formed by the coastal and oceanic branches of the Humboldt current, separated by the countercurrent from Peru.
The superficial dynamics of the area are dominated by the Permanent High Pressure Center of the Southern Pacific, whose variability, associated with the concept of Southern Oscillation, conditions the local characteristics of the Chilean sea.
The masses of water described in this area, present a transition zone on the surface where the Sub-Antarctic Water from the South meets with the Sub-Tropical Water which intrudes from the North West. Immediately beneath these there is an intrusion of Sub-surface Equatorial Water towards the South; in turn, Intermediate Antarctic Water flows beneath this towards the North.
In general, the area presents great variability in its characteristics, quickly showing the changes from the atmospheric system, which sometimes conditions the existence of cold flows, upwelling, high productivity; and other times warm flows, with invasion of sub-tropical waters and low productivity. It may be said that oceanographically the area is generally highly unstable.
DISTRIBUTION AND STRUCTURE OF POPULATIONS
Anchovy (Engraulis ringens)
Anchovy lives along the coasts of Perú and Chile. From Zorritos, 4°30'S (Chirichigno, 1974), as far as Chiloé, around 42°30'S (Brandhorst, 1963).
Along the Chilean coast it is caught mainly along a coastal strip of not more than 25 to 30 nautical miles; however, its distribution surpasses 50 nautical miles off shore.
Meristic, morphometric and marking studies, and reproduction areas indicate the existence of three populations: Center-North of Perú; South of Perú and North of Chile; and Center-South of Chile (Brandhorst, Carreño and Rojas, 1965; Tsukayama, 1966 and 1982; Rojas de Mendiola, 1971; Jordan and Málaga, 1971; Serra and Gil, 1975).
Mackerel (Scomber japonicus peruanus)
Mackerel is distributed in the South Eastern Pacific from Manta (0°45'S) and around the Galápagos Island (Chirichigno, 1974) south of Guamblin Island, as far as latitude 45°41'S, in accordance with observations made in April and May 1978 by A. Sanhueza (pers. com.).
Mann (1954) indicates that mackerel in Chile is present from the border with Perú as far as Valparaíso (33°S), but pointed out that it is rarely seen south of Taltal (25°20'S).
Catches are mainly obtained along a 60 nautical mile coastal strip. Catches obtained in the region by a fleet of Soviet factory ships indicate that the species is also found beyond 200 nautical miles. (Statistical Year-book, FAO. 1979 and 1980). This information is in agreement with the presence of larvae as far as 200 nautical miles (Rojas and Mujica, 1981).
There is not much information on the populational structure of mackerel in the region, except for the greater increase between hyaline rings of otolith of this species in Ecuador than in Chile, due to which it is assumed that growth is more accelerated in Ecuadorean waters (S. Pizarro and H. Steffens). On the other hand, information obtained from studies in spawning areas (Santander and Castillo, 1979; Serra et al, 1982; Rojas and Mujica, 1981) suggests the existence of two populations: Center-North of Perú and North of Chile.
Jack mackerel (Trachurus murphyi)
Jackmackerel lives along the coasts of Peru and Chile. It is distributed in the area from Lobos de Afuera Island (6°50'S) and around the Galápagos Islands (Chirichigno, 1974) as far as the mouth of the Strait of Magellan (52°30'S) (Bahamonde, 1978).
It is important to point out the longitudinal distribution of jack mackerel which goes beyond 200 nautical miles (catches of Soviet factory ships); it is found as far as 900 nautical miles from the Chilean coast in accordance with ichthyoplankton studies carried out by Rojas (1980).
The vertical distribution of jack mackerel may be very deep. In the northern zone it has been observed at depths of as much as 200 meters, and in the central-southern and austral zones at depths of 300 meters, where it appears in catches obtained with demersal trawls.
There are no studies nor background information available to indicate the number of populational units existing along the entire distribution area.
Common sardine (Clupea (Strangomera) bentincki)
Common sardine is found from the north of Coquimbo (29°S) as far as Puerto Montt (42°S) (Arrizaga, 1981). This species is mainly coastal and it is caught preferably in the area of Talcahuano (37°S), in gulfs and bays.
There are some meristic data (Brandhorst, Carreno and Rojas; 1965) and data on growth parameters (Aguayo and Soto, 1978) which suggest the existence of two populations of common sardine; one in Coquimbo and the other in Talcahuano.
Spanish sardine (Sardinops sagax)
Spanish sardine is distributed in an area from Southern Ecuador, where it is identified as Peruvian sardine, and around the Galápagos Islands (Chirichigno, 1974) as far as Corral (39°50'S) in the Center-South of Chile, in accordance with new records of Spanish sardine eggs in August 1981 (Rojas and Mujica, in preparation).
It may be stated according to available information that the geographic distribution of this species has changed. Chirichigno (1974) recorded Secchura By, in Northern Perú, as the northern limit of its distribution. In accordance with different authors the southernmost point at which it is found is:
- Tomé (36°30'S): Delfin (1900) and Fowler, 1945.
- Coast of Concepción (36°40'S): C. Oliver Schneider, 1943
- Mocha Island (38°20'S): Mann, 1945
However, other authors indicate that it was not found south of Coquimbo at the end of the fifties (De Buen, 1958) or at the beginning of the sixties (Brandhorst, 1963). This appears to be confirmed by observations carried out by biologists of the Fisheries Development Institute (IFOP), in the mid-sixties in Coquimbo, where although Sardinops appeared in the catches, Clupea was evidently dominant.
Subsequently, at the end of the sixties and beginning of the seventies, Sardinops began to predominate over Clupea in the catches, until the latter finally disappeared. Samplings of landings in Talcahuano from 1965 onwards, by IFOP, confirm the absence of Sardinops in that area in those years.
The longitudinal distribution of spanish sardine reaches 200 nautical miles. However fisheries are carried out preferably within the 60 nautical mile coastal strip.
There are no studies to distinguish the present populational structure, nevertheless, information drawn from the distribution of eggs and larvae (Rojas and Mujica, 1981) suggest the hypothesis that in Chile there are two populations, one in the northern zone and the other in front of Talcahuano. Spatial spawning patterns suggest the existence of another population distributed along the central and northern coast of Perú (Santander, 1981).
REPRODUCTION
It may be ventured on the basis of an analysis of the spawning seasons (Table 1) of anchovy, mackerel, jack mackerel, common sardine and spanish sardine, that there are two groups: the clupeids on the one hand, with bimodal spawning in the winter and spring and a secondary spawning in the summer; and on the other, mackerel and jack mackerel which ha only one spawning season, in the summer-autumn and spring-summer respectively.
| Species | Main Spawning Season | First Maturity | LM/L |
|---|---|---|---|
| Anchovy | July-August and December | 12 cm. L.t. | 0.63 |
| Mackerel | January-May | 30 cm. L.h. | 0.67 |
| Jack mackerel | October-February | 31 cm. L.h. | 0.48* |
| Common sardine | July-August and January | 11 cm. L.t. | 0.62 |
| Spanish sardine | August-October and February | 24 cm. L.t. | 0.57 |
* It was used L = 65 cm., L.t.= total length, L.h.= fork length.
The first sexual maturity of the described species occurs when they have reached from 50 to 67% of their asymptotic length, which is interpreted as an adaptive strategy in which the initiation of the reproductive process is retarded in favour of a greater use of energy in the process of growth.
It has been concluded from an examination of the gonads that all the species considered have a fractional spawning system (in batches).
In Chile two areas are considered as the most important spawning grounds of anchovy (Fig. 10), that is the northern zone (between the border with Peru and 25°S) and the area of Talcahuano (35°S to 38°S). In the northern zone spawning areas are close to the coast, mainly among a strip of 20 nautical miles. They may extend as far as 80-100 nautical miles from the coast. In Talcahuano the most important area lies between the Gulf of Arauco (37°10'S) and Punta Nugurue (36°S), and does not extend farther west than 10 to 12 nautical miles (Mujica and Rojas, 1980).
During 1980 ichthyoplankton surveys were carried out between the border with Perú and Coquimbo (39°S) and in the area of Talcahuano (Rojas and Mujica, 1981) which show the important changes in the geographic extension and intensity of spawning of anchovy in the north (Fig. 11). In front of Talcahuano the density of eggs and larvae remains at levels similar to those recorded in the sixties and beginning of the seventies.
Available information indicates that in Chile mackerel spawns mainly in the north, between the border with Perú and Antofagasta (24°S), although larvae have also been reported in front of Talcahuano (Rojas and Mjuica, 1981). Preliminary results of surveys carried out in 1981 and the beginning of 1982, suggest the existence of secondary spawning in the area around Talcahuano (37°S) in the months of September-October (Rojas and Mujica, pers. com.). Distribution of larvae towards the west exceeds 190 nautical miles.
Jack mackerel spawns along the Chilean coast as far as 41°S, which is the southernmost point at which samples have been obtained, not taking into account the distribution of eggs and larvae (Fig. 12). Available information indicates that the largest concentrations of jack mackerel eggs and larvae are located from Antofagasta to the south. Surveys along the Chilean coast were made as far as 200 nautical miles, recording important densities of eggs and larvae in the entire area surveyed, without cutting off its distribution towards the west. Rojas (1980) when analyzing samples of ichthyoplankton taken during a tuna survey in 1979 along the Chilean coast, found a high concentration of jackmackerel larvae in an area offshore of Talcahuano between 450 and 900 nautical miles. The density averaged 23 larvae per positive station, which constitutes a high stocking figure for this area. The characteristic of jackmackerel is its dispersed spawning pattern. The greatest number of eggs found per station was 2,400 (Rojas and Mujica, in preparation), which is a relatively small figure if compared with the maximum of 40,000 eggs recorded for Spanish sardine.
Fig. 10. Geographic distribution of anchovy eggs, 1964-1973. a) Spring-Summer spawning (November to January) b) Winter spawning (July to September) From Serra, Aguayo, Rojas, Canon and Inostroza (1970). Anchovy (Engraulis ringens). In: Estado Actual de las Principles Pesquerias Nacionales. Bases para un Desarrollo Pesquero. CORFO/Institudo Fomento Pesquero. Ap 79-18. 52 p.
Fig. 11. Anchovy spawning area in January 1980. From Rojas and Mujica (1981).
Fig. 12. Spawning area of jackmackerel.
A. August
B. September-October
C. November
D. February.
From Rojas and Mujica, (pers. com.).
The spawning area for common sardine is unknown (Serra, et al., 1979) and no ova have ever been found in the ichthyoplankton surveys carried out in the Central-Southern zone of Chile. This gives rise to the hypothesis that this species spawns on the bottom of the sea like its relative the herring does in the northern hemisphere. The greater concentrations of larvae in the area of Talcahuano (Gulf of Arauco, Bay of Concepeión) suggest that this is the main spawning area.
Spanish sardine, like anchovy, spawn in two main areas, that is: the Northern Zone and Talcahuano (Fig. 13). The maximum extension to the west is 80 nautical miles. Studies carried out by IFOP in the 1964-1973 period, between Arica and Chile (42°S), do not record eggs and larvae of Spanish sardine further South than 25°S. Balbontin and Garreton (1977) reported having found eggs of this species off Valparaíso in 1975. In figure 13 a comparison is made of the distribution of spanish sardine eggs collected in August for the 1963-1972 and 1981 period, which shows the changes that have occurred in the geographic distribution of spawning. In fact the spawning area of Talcahuano did not exist in the 1964-1973 period.
Fig. 13. Spawning area
of the spanish sardine.
A. August 1963-1972
B. August 1981.
From O. Rojas, pers. com.
GROWTH AND NATURAL DEATH RATE
Table 2 shows the parameters of the growth equation of Von Bertalanfly, maximum age observed in fisheries and the natural death rate.
| Method/year | 1977 | 1978 | 1979 | 1980 | 1981 |
|---|---|---|---|---|---|
| 1. Regression | 2.6530 | 1.8551 | 1.7575 | 1.8584 | 1.9966 |
| 2. S (Z) | 2.4232 | 1.8315 | 1.1555 | 1.6993 | 1.8328 |
| 3. Heincke | 2.0521 | 1.7166 | 0.7890 | 1.3244 | 1.4925 |
| 4. Robson and Chapman | 2.1436 | 1.7247 | 1.0321 | 1.4401 | 1.5670 |
| Average mortality | 2.3180 | 1.7820 | 1.1835 | 1.5806 | 1.7222 |
| Standard deviation | 0.2735 | 0.0715 | 0.4118 | 0.2427 | 0.2341 |
From Serra and Zuleta 1982.
The parameters for the Northern Zone and Talcahuano are shown below for jack mackerel. The maximum sizes of this species in the fisheries for fishmeal corresponds to samples of about 40 cm. fork length. In the sixties and beginning of the seventies there was a bonito and jack mackerel fishery in the northern zone for canning purposes; in this case jack mackerel of over 40 cm. fork length was caught as required by the factory. Maximum sizes exceeded 65 cm. fork lengths to a maximum of 72 cm. From the foregoing it may be concluded that the estimated K values for jack mackerel correspond to the fraction of the population which sustains the fishmeal industry. In order to obtain an approximate K value for the population, a new adjustment based on the Beverton method was made of the data on average length-age available for fish up to 11 years old and considering an arbitrary asymptotic length of 65 cm. fork length. The result obtained was K = 0.08, a value which is similar to that estimated for jack mackerel in California (K = 0.0935; Wine and Knaggs, 1975).
To estimate the natural death rate an empirical physiological equation proposed by Pauly (1980) was used. The results are shown in Table 3.
| Species | L | K | to | Tmax | M |
|---|---|---|---|---|---|
| Anchovy | 19.04 cm. | 0.73 | -0.647 | 4 años | 1.3 (17°C) |
| Mackerel | 44.62 cm. | 0.16 | -1.553 | 9 años | 0.3 (18°C) |
| Jack mackerel ZN* | 45.9 cm. | 0.167 | -0.882 | 11 años | 0.4 (18°C) |
| Jack mackerel T* | 44.3 cm. | 0.181 | -0.756 | 11 años | 0.4(15°C) |
| Common sardine | 17.85 cm. | 0.45 | -0.828 | 4 años | 0.5 (13°C) |
| Spanish sardine | 42 cm. | 0.19 | -0.8 | 11 años | 0.4(18°C) |
* ZN = Zona Norte (Northern Zone); T = Talcahuano
ABUNDANCE
Changes in abundance have been described using catches and catches per effort unit. Catches have been used on the assumption that there is a good correlation between the latter and stocks when the effort is high and there are no limitations to fishing volumes. The trend of catches for different species was already analyzed in the corresponding paragraph.
The catch per effort unit is the classical abundance index of fisheries studies. However, in recent years it has been determined that it is not a good index for the quantitative description of changes in pelagic fish stocks (Schaff, 1975; MacCall, 1976; Ulltang, 1976). Nevertheless, its consideration is useful to indicate the changes that have taken place, as may be seen in Figures 6, 9, 14 and 15, which represent a trend similar to that of catches (Fig. 2) for the different species. These changes were confirmed in the case of spanish sardine, for which an estimate of stocks was obtained expressed by the mean biomass, with data provided by virtual population analysis (Serra and Zuleta, 1982). The changes in the mean biomass are shown in Figure 16, where the increase in spanish sardine stocks from 1974 onwards with a similar pattern as that of catches per effort unit may be seen.
Fig. 16. Change in the mean biomass of the Chilean spanish sardine (1974-1981) estimated by VPA (from age 3). From Serra and Zuleta (1982).
At the same time that mackerel, jack mackerel and spanish sardine stocks were increasing, anchovy collapsed in the Northern Zone in 1977, its stocks having decreased substantially already in 1972 (Fig. 6), and of the mixed resource of common sardine and anchovy in Talcahuano in 1975-1976.
In accordance with the above catches and catches per effort unit are useful in describing the explosive growth phase of these resources qualitatively. However, their use is considered to be limited in describing their stabilization and decline.
There are estimates of spanish sardine stocks for recent years based on the hydroacoustic method and on the virtual population analysis (Serra and Zuleta 1982). Estimates made with the hydro-acoustic method in the area from the border with Peru as far as 24° latitude South and 200 nautical miles, show a biomass of 5,500,000 and 5,100,000 tons in 1981 (June-July) and 1982 (July-August) respectively. The mean population biomass for the years 1974 to 1981 was obtained on the basis of virtual population analysis. Results indicate that spanish sardine stocks, age 3 and above, were at a level of 8,500,000 tons in 1980 and 1981, and around 8,000,000 tons in 1978 and 1979. The difference with the results obtained with the acoustic method is being analyzed.
Fig. 14. CPUE of mackerel, jack mackerel and spanish sardine of Chilean pelagic fishery of the northern zone. 1965-1981. From Serra (1981).
Fig. 15. Catch per unit effort of the anchovy-common sardine resource from Talcahuano. C/VCPE = catch per standard trips with catch; C/TVE = catch per total standerd trips. From Serra (1978).
EXPLOITATION AND MANAGEMENT
Serra (1978; in press) applied the Schaefer model and the general production model of Pella and Tomlinson (m=2) to the data on catches and effort in mixed common sardine and anchovy fisheries in Talcahuano and anchovy in the Northern Zone respectively (Fig. 17 a; b). In both cases the models did not adjust, if the entire series of years was considered, which was finally achieved by eliminating the last years.
The explanation for this non-adjustment is that the catch-effort relation in both cases curves toward the origin. This happens mainly because the effort does not represent the fishing mortality rate, as the capturability coefficient (q) varies in an inverse proportion with abundance (Gulland, 1976).
A depensatory catch-effort curve was overlaid on the data for both fisheries (Fig. 17), from which it is possible to conclude that, without regulations, these fisheries come very close to the critical level defined by the depensatory catch-effort model when they reach their maximum catch levels. Any environmental disturbance or a greater fishing effort are enough to cause the resource to collapse.
From the above it may be concluded that the levels of exploitation reached in anchovy fisheries in the Northern Zone and in common sardine-anchovy in Talcahuano were too high, and this could explain the great fluctuations in catches (Fig. 2 and 3). The studies carried out by Serra (1978; in press) conclude that fishing cannot be disregarded as an important factor responsible for the collapse of these fisheries.
In spite of the accelerated development of these fisheries and their subsequent collapse, no regulatory measure was applied and mention can be made only of an effort of the Department of Fisheries and Game of the Ministry of Agriculture, responsible for fisheries management, to introduce a restriction on the size of anchovy in 1965, which finally did not prosper because it lacked a sound enough technical basis and the elements needed for its application. Later, during the 1972 and 1973 crisis caused by "El Niño" phenomenon, no regulatory measures were taken either, at least legally. However, there was an agreement between the Ministry of Fisheries of Peru and of Chile to establish a moratorium of one week on anchovy fisheries in the Northern Zone, if fish of less than 11.5 cm. exceeded 20% of the landings of fishing activities in the area between Ilo (Southern Perú) and Arica (Northern Chile). Concretely, this measure was never applied and the agreement lasted until 1973, when a change took place in the political regime of Chile. In addition, there were two military edicts, originated by the Regional Government and outside of the institutional framework of fisheries administration. The first one, in December 1973, established a one month moratorium for Arica and Iquique and the second, in December 1977, prohibited industrial fisheries in the coastal areas of Iquique, for the purpose of avoiding conflicts between artisanal and industrial fishermen.
In 1981 an analysis was made to determine the state of pelagic resources in the Northern Zone (SUBPES), 1981; Serra, 1981), for which all information available was taken into account, such as patterns of landing curves in similar fisheries, catch per effort unit, modal sizes, depensatory model of catch-effort and exploitation rate in the case of the spanish sardine, the only species for which the age structure of the landings was known. All of this information was integrated to make a diagnosis of fisheries. The situation of the fishery was considered to be of great risk on the one hand, catches were increasing too rapidly, especially those of spanish sardine, mackerel catches decreased, the growth of catches per effort unit stopped, modal sizes of spanish sardine and jack mackerel decreased; and on the other because of the absolute ignorance regarding the recruitment strength.
In the case of spanish sardine an exploitation rate of 43% was estimated, which was excessive in accordance with the criterion defined as the adequate level of exploitation, that is when F=M, and is the result of empirical evidence provided by the analysis of various similar fisheries in the world (Troadec, Clark and Gulland, 1980).
Fig. 17a. Catch-effort curve of the anchovy-common sardine
of Talchaunao.
From Serra (1978). Depensatory curve fitted by hand.
Fig. 17b. Catch-effort curve of the Zona Norte anchovy
fishery.
From Serra (in press). Depensatory curve fitted by hand.
When considering this situation, the Under-Secretariat of Fisheries concluded that it was necessary to adopt management measures, to decrease the exploitation rate of the resources and increase their probability of permanence at satisfactory levels of abundance for fisheries activities.
In accordance with the above three regulations were adopted:
a) Fixation of a minimum size for spanish sardine (20 cm. total length) and jack mackerel (26 cm. fork length).
The minimum size was estimated on the base of the criterion of critical age, to make a more efficient use of the growth of the species (overfishing by growth) at the same time increasing the expectation of an individual to reach adulthood (Decree Law No. 458).
b) Prohibition of the use of purse-seines with nets over 20 fathoms deep and a mesh size equal to or less than 38 mm., along a coastal fringe of one nautical mile (Decree Law No. 459).
Knowledge on the spacial distribution of anchovy, mackerel and spanish sardine indicates that their breeding areas lie along the coastal fringe. Thus, the recruiting force is protected.
c) Determination of a quota of allowable catches for spanish sardine in the northern zone for 1982.
The allowable catch quota was calculated using the catch equation of Boranov and assuming that the biomass existing in 1982 was the same as in 1981.
First a projection was made of spanish sardine catches for 1981, based on available data up to September of that year and on seasonal patterns observed during 1978, 1979 and 1980.
Then a 39% exploitation rate was established as a gradual approximation to the adequate level of 30%, which results when F=M and M=0.4. The quota calculated was of 1,300,000 tons.
Finally, it is necessary to explain that the application of an allowable catch quota caused conflicts because it was completed before the end of the period for which it had been established. Consequently, the quota was supplemented with 116,000 tons (Decree Law No. 263), which represents the establishment of a 42% exploitation rate, in accordance with the estimates made. This supplement was also completed before the end of the fishing season.
Fishing entrepreneurs started negotiations with the authorities in connection with the socio-economic problem that would originate if spanish sardine fisheries were stopped. This situation, which was aggravated by a severe recession in the national economy, presented the authorities with the dilemma of favouring the activity or applying the regulation. The first alternative was chosen, finally increasing the catch of spanish sardine in the northern zone to 1,650,000 tons in 1982.
During 1982, with a longer series of years (1974 to 1981) with an age structure, new estimates were obtained on the total instantaneous mortality rate (Z) and on fishing rate (F) (Serra and Zuleta, 1982). The results (Tables 2 and 4) confirmed the analysis made in 1981 (Serra op. cit.), in the sense that the values of Z and F are too high for the fraction of population recruited into the fishery, age 7 and above. The new results obtained are even higher than those of 1981, the exploitation rate increasing up to levels of 70% for some years.
| 1974 | 1975 | 1976 | 1977 | 1978 | 1979 | 1980 | 1981 | |
|---|---|---|---|---|---|---|---|---|
| 3 | 0.00024 | 0.00001 | 0.00002 | 0.00011 | 0.00751 | 0.00000 | 0.00023 | 0.00050 |
| 4 | 0.00411 | 0.00018 | 0.00038 | 0.00052 | 0.00678 | 0.01485 | 0.00787 | 0.00900 |
| 5 | 0.07645 | 0.01386 | 0.00846 | 0.01144 | 0.02218 | 0.12036 | 0.14108 | 0.13000 |
| 6 | 0.32767 | 0.13629 | 0.04695 | 0.12513 | 0.11698 | 0.42851 | 0.57233 | 0.42000 |
| 7 | 0.94997 | 0.38887 | 0.23893 | 0.41998 | 0.36970 | 0.96075 | 0.91837 | 1.10000 |
| 8 | 1.65367 | 1.02590 | 0.38641 | 0.91470 | 0.92693 | 2.08525 | 1.33174 | 1.37000 |
| 9 | 3.20798 | 1.65268 | 1.02813 | 1.07590 | 1.45110 | 3.24382 | 2.13925 | 2.34000 |
| 10 | 2.60000 | 2.60000 | 2.60000 | 2.60000 | 2.60000 | 2.60000 | 2.60000 | 2.60000 |
| 3+ | 0.03706 | 0.01924 | 0.01515 | 0.03999 | 0.04959 | 0.24315 | 0.13959 | 0.12800 |
From Serra and Zuleta (1982) with VPA.
However, on the other hand virtual population analysis provides optimistic prospects due to abundance of the resource and because no decrease is evident in the strength of the year classes that are entering the fishery (Table 5).
| 1974 | 1975 | 1976 | 1977 | 1978 | 1979 | 1980 | 1981 | |
|---|---|---|---|---|---|---|---|---|
| 3 | 1163670 | 1203520 | 1660080 | 2563420 | 2326160 | 2349410 | 2420170 | 2566370 |
| 4 | 1032600 | 1137300 | 1176130 | 1622190 | 2497610 | 2248920 | 2287930 | 2355600 |
| 5 | 522397 | 909793 | 1004560 | 1037420 | 1423740 | 2087530 | 1853980 | 1902760 |
| 6 | 157316 | 390724 | 733148 | 783198 | 810543 | 963018 | 1259630 | 1180390 |
| 7 | 37366 | 87322 | 257537 | 468352 | 490216 | 399213 | 405600 | 455387 |
| 8 | 9659 | 10718 | 45260 | 116629 | 190721 | 136823 | 101475 | 104341 |
| 9 | 1723 | 1375 | 2855 | 17266 | 28444 | 27097 | 12437 | 14313 |
| 10 | 389 | 60 | 143 | 443 | 2600 | 3378 | 913 | 932 |
| 3+ | 2925130 | 3740810 | 4879710 | 6608920 | 7770040 | 8215390 | 8342140 | 8580100 |
From Serra and Zuleta (1982) with VPA.
Preliminary data on the stock-recruit relationship (Fig. 18) indicate that recruit ment has been independent (nearly constant) of the size of the stock for the points considered, but this also means that the number of recruits per spawning fish has decreased together with the growth of the parent stock.
Fig. 18. Stock-recruit relationship of the spanish sardine.
DISCUSSION
The above shows very clearly the drastic changes that have taken place in Chilean pelagic fisheries. After the collapse of the anchovy and of the common sardine-anchovy resources in the northern zone and Talcahuano respectively, there was an unexpected and fortunate increase in spanish sardine, jack mackerel and mackerel stocks. Fisheries in the northern zone changed from a practically mono-specific system, in which anchovy dominated, to a multi-specific system with the dominance of spanish sardine. In Talcahuano the system changed from the dominance of the mixed common sardine-anchovy resource to that of jack mackerel. It is possible that in both cases it would be more appropriate to speak of succession or successional fisheries instead of multi-specific fisheries.
It is important to point out that after the changes in dominance in both fisheries, total yields reached maximum levels a little over twice as much as those reached in the previous systems, for which there is no clear explanation.
Simultaneously with the change in the abundance of the species, a change took place in their geographic distribution and in the size of the spawning areas. The most spectacular case is probably that of spanish sardine, this species "colonized" (Kondo, 1980; Sharp, 1980), the area toward the south which it invaded, and even established a new spawning area. It is interesting to note that here also the association of abundance and spatial distribution in this type of resource was effected.
Data provided by Santander and Castillo (1979), Santander (1981), Tsukayama (1982) show similar changes in Perú.
The five species analyzed have similar natural history patterns; they are all iteroparous reproducers and their parameters of longevity, growth and age at first maturity form a consistent pattern (Tables 1 and 2), in agreement with what has been established by Beverton (1963). However, differences may be observed in the spatial patterns of spawning, mainly between clupeids (anchovy and spanish sardine) and jack mackerel. The first have defined spawning areas (Fig. 10 and 13), with focal points with high densities of eggs. As many as 40,000 eggs per 10 square meters having been reported for spanish sardine. Jack mackerel, on the other hand, has a more dispersed pattern (Fig. 12), reproductive products being distributed over a far greater area. The maximum density recorded is of 2,400 eggs per 10 square meters. Curiously, the growth rate of jack mackerel at the embryo and larva level is the slowest of the genera represented (Theilacker and Dorsey, 1980). If the spawning area of jack mackerel spreads from 24°S as far as 40°S and from the coast will beyond 200 nautical miles, and so far great concentrations of eggs and larvae have not been clearly identified; is it possible to define what conditions are the most suitable for the survival of embryos and larvae, and to know the requirements of density of food particles and conditions associated with the stability of the ocean. Bakkun and Parrish (1982) determined that the area in which jack mackerel spawns is highly turbulent and has strong Ekman transport. Contrarily, anchovy, spanish sardine and mackerel, have their main spawning grounds between the border with Perú (Arica) and antofagasta, an area which has been described to have great ocean stability (Bakkun and Parrish, 1982), in the terms of Lasker (1981). The second most important spawning ground of anchovy, spanish sardine and also the most likely spawning ground of common sardine, is the area of Talcahuano (37°S) where spawning takes place close to the coast, protected by gulfs and bays from the more unfavourable conditions away from the coast where jack mackerel spawns (Fig. 12). It is even postulated as a hypothesis that common sardine spawns on the bottom of the sea.
It may be concluded from the foregoing that all these species present a fractioned spawning pattern, in batches, with relatively large reproductive periods, and an exploratory reproductive behaviour of the habitat in time and space due to the variability and unpredictability of climatic conditions.
In spite of environmental variability, clupeids and probably mackerel, concentrate their spawning in the more favourable areas which are those of greater stability, and jack mackerel, on the other hand, seeks areas which appear to be more unfavourable, in accordance with existing knowledge, where it disperses its reproductive material.
The behaviour of the adult jack mackerel population which is scarcely represented in the fishery, is concordant with this spawning pattern. It may be concluded from the information on distribution of this species, its spawning pattern and the size structure in the landings, that this fishery is sustained only by a sector of the population, that is, mainly by individuals between 26 and 34 cm. fork length (4 to 8 years of age). Projecting age studies on T. symmetricus carried out in California, 70 cm. fork length individuals are over 25 years old (MacCall, et al., 1980). The missing fraction of the adult stock, changes its behaviour, and apparently migrates to the high seas (catches by Soviet ships) and probably also disperse forming small schools (large jack mackerel caught by artisanal fishermen and by a small fleet of bonito boats at the beginning of the seventies). In this sense the characteristics of this fraction of the population is its dispersion, which is consistent with the spread of the geographic area observed in connection with the spawning grounds, which is not explained by the phenomenon of egg diffusion.
It may be concluded from available data that exploitation levels of anchovy in the northern zone and of common sardine-anchovy in the Talcahuano area were too high, in accordance with present knowledge on pelagic resources. In this regard, it is not possible to blame only environmental changes for the collapse of these resources, fishing also being responsible. Nevertheless, it is surprising to notice that when these resources are in the phase of stock growth they can support high fishing rates, as those observed from 1974 onwards in the case of spanish sardine from the age of 7, this being the age group in which this species is totally recruited in the fishery (Table 4), no apparent negative effects to their expansion having been observed.
The history of these fisheries does appear to indicate however, that the combination of a high exploitation rate with adverse environmental conditions is extremely dangerous to the maintenance of adequate stock levels for fisheries.
ACKNOWLEDGEMENT
I would like to acknowledge the advice given by Mr. R. Kelly on the oceanographic features; Mr. O. Rojas and Mr.A.Mujica for lending some figures on spawning areas; and to the Fisheries Department Institute (IFOP) for its useful collaboration.
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