Feeding of Greenland Halibut (Reinhardtius hippoglossoides) in 3LMNO NAFO Regulatory Area Divisions (Northwest Atlantic), 1991-94

Feeding of Greenland halibut in Flemish Pass and Newfoundland's Grand Bank slope (3LMNO NAFO divisions) was studied from on board commercial fleet analysis, from June 1991 to December 1994. Percentage of empty stomachs from 625 165 specimens and frequency of occurrence of prey from 18 527 stomachs, were used to evaluate feeding intensity and importance of prey groups. Examinationrevealed increasing feeding intensity with sin. The emptiness percentage varies with depth, in a directly proportional way, in specimens of less than 60 cm, and is inversely proportional in those of over 70 cm. A smaller percentage of empty stomachs was found in females than in males, upwards of the length of first maturity of the latter, as well as a decreasing feeding rate as females become reproductively active. Analysis of frequency of occurrence of main prey groups indicated a change in Greenland halibut feeding at 60 cm in all divisions, a change which supposes a fall in consumption of 0161w:elms and molluscs, an increase in fish and (fiat and an increase in prey species size. the difference between divisions is due to the consumption of Mallows yillosus by specimens of less than 60 cm in divisions 3NO : There are also significant changes with depth of around 1000 m in the diet of Reinhard/ins hippoglossoides of less than 60 cm, bringing about a substitution of capelin for decapod cephalopods At great depths squid have a similar role in the diet of Greenland halibut to that played by capelin on the continental shell The variation of the prey species is related to their disnibution. Offal arc an extra provision of food introduced by fishing activity, making up the second most important prey group in specimens of over 60 cm

Report on fisheries mangement in international deep sea water and its biodiversity conservation

It is a repport on the FAO "Analysis and guide for the implementation of international and policy instruments related to deep sea fisheries and biodiversity conservation in ABJN (Areas Beyond National Jurisdiction)” of 27th June 2016

Spanish Research Report for 1994

13 páginas, 12 tablasPeer reviewe

Greenland Halibut Depth Variations of Catch-per-unit Effort, Length Composition, Mature Proportions and Associated By-catches in Divisions 3LMNO

In this paper we present a review of the geographic and bathimetric patterns of occurrence of the Greenland halibut catches in NAFO Divisions 3LMNO and their incidence on the catch of other stocks, namely cod, American plaice and yellowtail and witch flounders. The Greenland halibut mature proportions at depth in both the commercial catches and the spring Spanish 3NO survey indices are also presented. According to the results of the Spanish fleet, the Greenland halibut fishery does not overlap significantly with either American plaice, yellowtail flounder, skate or cod. By-catches of witch flounder in the Greenland halibut fishery have been very small, at least in 1999. The CPUE analysis indicate that Greenland halibut is best caught in the deepest strata, with catch rates comparatively poor at depths less than 600 m. Besides a sharp change in catchability is observed between 500 – 600 m. The proportion of mature fish in the catches increases with depth attaining a maximum between 1200 – 1600 m. The survey results indicate that most part of the SSB is found at depths beyond 800 m

An Assessment for Roughhead Grenadier (Macrourus berglax) in NAFO Subareas 2 and 3.

It has been recognised that the recent catches of grenadiers by EU-Portugal and EU-Spain in Subarea 3, previously reported to NAFO as roundnose grenadiers, correspond to roughhead grenadier. Roughhead grenadier is taken as by-catch in the Greenland halibut fishery in the Regulatory Area mainly in Divisions 3LMN. Catches increased gradually and the largest proportion by country correspond to Spain and Portugal, with 6050 t. and 1089 t. respectively in 1998. A review of the biomass estimates from the available research surveys in Subareas 2 and 3 is presented. According to the Canadian fall surveys, it seems that the main part of the stock shifted from the northern Divisions (2GJand 3K) to the southern ones (3LN), and to greater depths (beyond 1000 m.) since early 90s. A review of the biological information available for this stock is also presented. Mean lengths (preanal fin lengths) of the catches show no decreasing trend since 1995. The age o fully recruitment to the fishery is 8, and the total mortality estimate (1997-1998) is Z = 0.43. Female age at maturity is 15, corresponding to a PFL of 26.5 cm. The Canadian fall survey series seems to be the best input for the assessment of this stock. At present the higher part of biomass is found in Div. 3L and 3N and at depths between 1000-1200 m. A yield per recruit has been performed using the input data presented in table 13. The partial recruitment vector comes from Cárdenas et al. (1995), The maturity curve at age from Murua and Motos (1997) and the mean weight at age from the 1998 agelength key. M is assumed as constant through the ages with a value of 0.2. The results of the yield per recruit analysis appears in Fig. 6. The estimated Fmax is 0.27 and F0.1 is 0.13. However it must be noted that this output is sensitive to possible changes in M, as if for instance M would be different between sexes, as suggest the results from Murua et al. (1999) and as it has been shown in the Greenland halibut (Anon. 1998). Any decreasing trend in the mean lengths, that would be an index of an excessive fishing pressure, is observed in the mean lengths of the catches since 1995 up to now. The available time series of catches at age is too short to analyse trends in the SSB, however it can be noted that only a 18 % and 10 % percent of the 1997 and 1998 catches respectively were above the female age at maturity (15 years). We have scarce information at the moment to assess an appropriate exploitation level, though survey series shows that at the current exploitation rate the biomass is increasing since 1994

Preliminary Results from the 1997 Bottom Trawl Survey in the NAFO Regulatory Area for Divisions 3NO

As the previous years, a stratified-random bottom trawl survey was performed in NAFO Regulatory area (Division 3NO) during 26th April to 17th May. The survey, which covered offshore areas on the Grand Bank, was conducted following the same procedures and the same vessel and gear of the 1995 and 1996 surveys (Paz et al. 1995; 1996). The area and the strata to be covered by the survey were based on the stratification charts and tables in Bishop (1994)