Tables 2 to 5 summarize all the catch data available at the meeting, based on the CECAF Statistical Bulletin, the Shimura reports (1980 and 1981) and new data presented during the meeting. Several errors in the CECAF Bulletin were corrected.
The data available concerned total catches for Divisions 34.1.1, 34.1.2 and 34.1.3 and fishing effort expressed in fishing hours for Division 34.1.3 (Table 6). The data were obtained per fishing day and were converted into fishing hours based on 20 fishing hours per day. Since 1978 the Spanish fleet has confined itself to Division 34.1.3 and only to the Dakhla zone. Most of these vessels belonged to the 250 to 309 gross tonnage class and their octopus harvests were 676 kg/h in 1980, a level comparable to that of 734 kg/h found by Shimura as an average for this vessel category making landings at Las Palmas. Fishing yields (cpue) seem to have doubled from 1980 to 1981.
The new cpue time series presented replaced that used previously. It would be desirable that Spain, which has a per ship data series, should make a study on standardization of the fishing power of these vessels.
Statistics before 1980 have been considered scarcely reliable.
The participants noted that the Moroccans offered to supply earlier data. At present the fishery is limited to the Dakhla zone (23° to 26°N, Division 34.2.3), the same as that fished by the Spanish fleet. Table 7 summarizes Moroccan catches and some cpues provisionally based on a small sampled of five ships. According to these data there are apparently two fishery strategies, one exploiting octopus and the other mainly squid. A comparison between 1980 and 1981 also shows an increase of harvests, although less marked (1.2x) than that attained by the Spanish. The data obtained by Shimura for 1980 at Las Palmas were also mentioned. Yields were generally higher than those indicated in the official Moroccan statistics. The Moroccan statistics covered 65 ships active in the zone. It was noted, however, that 10 to 15 active ships were not covered.
In 1980 for the first time Korea declared its statistics by fishing zone as recommended by the last ad hoc Working Group on Assessment of Cephalopod Stocks (October 1980). These data are compared to those collected at Las Palmas by CECAF (Shimura, 1981) in Table 7. The CECAF total catch data were systematically higher, but referred to all ships (17.9 × 1 000 fishing days) whereas the Korean official statistics covered only 4 100 fishing days.
For Senegal the statistics after 1976, which were presented in the CECAF Statistical Bulletin, were corrected taking into account the new data of Bakhayokho (1981).
Catches for other countries were generally small (Tables 2 to 5).
Spain was able to obtain and present Spanish monthly catch composition for octopus; sampling of the weight frequencies of each category, based on stratification of commercial landings in eight categories, was done by Japanese importing companies; it was obtained by hundred gramme weight class. For squid and cuttlefish we now have catch per commercial category statistics for the same Spanish fleet, without size sampling in each category. These statistics cover the 1976 to 1980 period. There may be a bias in the data as a result of frequent under-sampling of small and large-sized octopus due to the lower market value of these categories.
Concerning cuttlefish we also noted high species mix in the smallest category (about 50 to 70 percent for species not belonging to Sepia officinalis). The results of research ship campaigns could supply an evaluation of specie composition of these small “cuttlefish”, provided that the comparison of results of a catch specie composition between research and commercial vessels showed that this method was valid.
The Group therefore recommended that a comparison be made of the specie composition of commercial and scientific catches of small “cuttlefish”.
Only the Spanish landings were covered by these statistics. The Group considered that these results followed the recommendations of the preceding Working Group and were highly useful to analyse the state of stocks, particularly those of octopus. However, the Group regretted that only the Spanish fleet was able to supply these data; it would be necessary, in particular, to know size structures of octopus fished at Cape Blanc so as to compare them to those of Dakhla (of the Korean fleet in particular). Furthermore, in the Dakhla zone the Moroccan fleet could not be sampled yet due to the fact that all the Moroccan landings were made in the Canary Islands. It was not known whether the size composition of these Moroccan catches was comparable to those of Spain. Therefore it would be highly desirable to obtain Moroccan samples following the same procedure as that employed by Spain. As long as these results remain unavailable it will be difficult to interpret evaluations by analytic models, which require catch age structure. Parallel to the sample of commercial catches, which was presented this year, size samples had been taken since 1980 on the Moroccan research ship IBN SINA. The 26° to 21°N zone was surveyed by this ship in a Spanish/Morocco cooperation programme. A ship equipped with a Spanish type of trawl conducted five campaigns in March and June 1980, March and June 1981 and November 1981. From 42 to 70 stations set radially perpendicular to the coast were surveyed in this way. The depth explored, varying from 20 to 110 m, was the same as that of the commercial fleets, as was the mesh size used (60 mm). The density of the radials varied so as to under-sample some zones and better analyse the geographic variability of the distribution (of sizes and densities). The results were stratified by geographic area. They showed a high seasonal variability of the size of the octopus fished; in November 1981 large quantities of the recruits born in springtime appeared. These campaigns also showed the presence on bottoms of more than 100 m in the Cape Barbas zone of large concentrations of “giant” (over 15 kg) octopus on grounds not trawled commercially because of the hardness of the bottom. Size distribution variability was not presented but is currently being studied.
The Group also noted that Spain had previously conducted research campaigns on commercial vessels in the same sector in January and February 1976 and 1977, May, September, October, November and December 1977, February-March 1978, July 1978, March and April 1979. The results of these findings were published in 1980 by Pereiro and Bravo de Laguna.
All these results refer to the Dakhla area only, excluding the Cape Blanc zone.
The Working Group recommended that size samples be taken in this sector on research ships and in commercial fisheries (Korean in particular) based at the Nouadhibou laboratory.
The samples taken during scientific surveys on cuttlefish of the Senegal area were presented. There are cuttlefish on the Senegal-Gambia shelf between 15° and 11°N. The largest sizes both of males and females exist mainly in the northern part of the region. (It seems that this distribution can be explained by sedimentology).
The size samples of Senegalese catches presented to the Working Group have been taken regularly since 1978. Artisanal and industrial fisheries are both sampled but by different procedures, the catches of industrial fisheries, like those landed at Las Palmas, being stratified by commercial categories.
