Stomach contents of North-East Arctic cod and possible changes in the diet the last years

A stomach sampling program has been carried out in connection with the construction of a multispecies modell for the Barents Sea. The results on the contents of 8410 cos (Gadus morhua) stomachs sampled in 1982-1985 are presented. The samples were collected by bottom- and pelagic trawl onboard Norwegian research vessels during routine surveys in the Barents Sea and the Spitsbergen area. For cod > 20 cm the major prey species in percent wet weight of the stomach content were capelin (Mallotus villosus) (40 %), deep sea shrimp (Pandalus borealis) (20 %) and redfish (Sebastes spp. ) (7 %). Capelin was the dominating prey species during the first part of the year. In the diet of smaller cod the most important prey species were shrimp (13 %), krill (Euphausiacea) (9 %), amphipods (16 %) and other small crustaceans (11 %). Since 1982 there has been a drop in the average stomach contents weights of cod > 20 cm in periods with a high content of capelin and since 1984 the relative importance of deep sea shrimp as prey species has been reduced. A preliminary estimate of the cod’s annual food consumption shows a consume of 2-3 times the biomass of the cod stock

Comparison of Norwegian and Russian trawl performance: Preliminary analysis of cod data

Working Document to the Arctic Fisheries Working Group 21-23 April 199

Vitenskapelig navn på 1495 europeiske marine dyr og planter med NODC tallkode, norsk og engelsk navn

Rapporten forklarer prinsippet for den taksonomiske 10-siffers tallkoden fra National Oceanographic Data Center (NODC), USA. Det er fire kataloger i rapporten. En er sortert etter tallkoden, en etter vitenskapelig navn, en etter norsk navn og en etter engelsk navn. Fire dataprogram som leser og oversetter tallkoder til Ønsket type navn er tatt med

Diet overlap between North-East Arctic cod and haddock in the southern part of the Barents Sea in 1984-1986

The diet composition of North-East Arctic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) are examined from stomach content data. Fish were collected in the southern part of the Barents Sea from 1984 to 1986. A total of 4790 cods and 1361 haddocks were divided according to season (winter, spring and fall) and fish size in 10 cm size classes. Only fish bigger than 10 cm length were considered. Diet overlap between the two species for each size group in each season was calculated using the Schoener's index. North-East Arctic cod show a size dependent shift in the diet. Fish smaller than 20 cm prey mainly on crustaceans (euphauiids, deep sea shrimp and amphipods). Above 20 cm, cod incorporate fish in the diet to a larger degree, the degree increasing with the size of the predator. Some seasonal changes are described. Haddock, a less ichthiophagous, bivalves and polychaetes. In general the diet overlap is low except in spring and fall when the smaller size groups of both species prey on euphausiids. The results are compared with previous information on cod-haddock interaction

The cestode parasite Grillotia Angeli as a biological tag for mackerel in the eastern North Atlantic

The trypanorhynch cestode Grillotia angeli Dollfus, 1969, infects mackerel Scomber scombrus L. up to the age of two years and survives thereafter as an encvsted plerocercus for as long as the mackerel lives. In the eastern North Atlantic infection can only take ilace in and to the south of ICES sub-area VII, ie to the south and west of Britain and Ireland. In year classes 1977 and earlier, 13.8% of mackerel which originated from nursery grounds in sub-area VII were infected with -G. angeli; in yLar classes 1978 and later, prevalence decreased to 1.2%. Data from year elasses 1977 and earlier indicate that: (1) mackerel caught off the north coast of Spain (sub-area VIII) and off Portugal (sub-area IX) were of dif ferent nursery origin from those caught further north; (2) mackerel caught in the southern North Sea (Division IVc) were predominately of southwestern origin; (3) to the northwest of Scotland (Division VIa north of 58ON) the proportions of mackerel of southwestern origin decreased from approximately 50% in September to 10% in January-February, then increased to >50% in March-April; (4) approximately 30% of all rnackerel caught in the Norwegian Sea (Division IIa) and the northern North Sea (Division IVa) were of southwestern origin. Brevalence data from different areas suggest that mackerel of year classes 1978 and later from southwestern nursery grounds have been migrating into northern areas in greater numbers than earlier year classes

Diet overlap between North-East Arctic cod and haddock in the southern part of the Barents Sea in 1984-1986

The diet composition of North-East Arctic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) are examined from stomach content data. Fish were collected in the southern part of the Barents Sea from 1984 to 1986. A total of 4790 cods and 1361 haddocks were divided according to season (winter, spring and fall) and fish size in 10 cm size classes. Only fish bigger than 10 cm length were considered. Diet overlap between the two species for each size group in each season was calculated using the Schoener's index. North-East Arctic cod show a size dependent shift in the diet. Fish smaller than 20 cm prey mainly on crustaceans (euphauiids, deep sea shrimp and amphipods). Above 20 cm, cod incorporate fish in the diet to a larger degree, the degree increasing with the size of the predator. Some seasonal changes are described. Haddock, a less ichthiophagous, bivalves and polychaetes. In general the diet overlap is low except in spring and fall when the smaller size groups of both species prey on euphausiids. The results are compared with previous information on cod-haddock interaction

Some exploratory XSA runs for NEA-saithe (using FLR)

Working Document # 10 WKROUND, 9-16 February 2010S.E_Log q residuals and scaled weights from XSA diagnostics are presented together with estimates of Fbar and SSB in the final assessment year for 10 different single and multi fleet runs. The purse seine tuning series showed the highest S.E_Log q residuals and lowest scaled weights and did not seem to perform any better than in previous analysis. It is therefore doubtful if there are any strong reasons to reintroduce this tuning series in the assessment. The acoustic survey indices got best results for the youngest age groups, but seem to perform reasonably well for older ones also, and it could be considered to extend the age span to age group 9. When it comes to the six different trawl CPUE tuning fleets, the one including all vessels above the median length, days with >20% and <80% saithe and averaging over Q1-4 seems to give the best and most stable results, though there are only minor differences between some of the series. One of the series based on the 7 vessels proposed by the industry also performs reasonably well. However, as pointed out in another WD, there are both holes and outliers in the data basis from the 7 vessels, and for the time being it is perhaps best to use time series based on more vessels. The CPUE indices got higher scaled weights in the XSA for older ages, while for age- groups 3-4 this tuning fleet is down-weighted. Age group 3 is rarely represented in landings for the later part of the time period 1994-2008 and should not be included in the tuning series, and perhaps age group 4 also should be excluded. S.E_Log q residuals and scaled weights for age group 9 are in the same range as for age group 9 from the survey, while age group 10 indices from the CPUE series got higher scaled weight in the XSA. However, regarding the high S.E_Log q residuals for age group 9, both age groups could be left out in the CPUE tuning series

Relations between recruitment indices and occurence in cod stomachs of pre-recruits of cod and haddock in the Barents Sea

Precision and relevance of pre-recruit studies for fiskery management related to fish stocks in the Barents Sea and adjacent waters. Proceedings of the sixth IMR-PINRO Symposium Bergen, 14-17 June 1994.The predation by North-East Arctic cod on pre-recruits of cod and haddock is reviewed based on data from the joint PINRO-IMR stomach content data base. It is investigated how the abundance indices from surveys of pre-recruits are correlated with the occurence in cod stomachs of pre-recruits of these species. Estimates of the consumption of cod and haddock by cod based on a new model for the stomach evacuation rate of cod are also given

Botnfiskundersøkingar i Barentshavet (redusert område) vinteren 1998

A combined acoustic and bottom trawl survey to obtain indices of abundance and estimates of length and weight at age has been carried out each winter (4-6 weeks in January- March) since 1981 in the Barents Sea. The target species are cod and haddock, but in recent years abundance indices have als0 been worked out for the redfish species and Greenland halibut. Since 1993 the survey area has been extended to the north and east in order to obtain a more complete coverage of the younger age groups of cod. In winter 1997 only the Norwegian part of the Barents Sea was covered, while in 1998 also a small part of the Russian EEZ was included in the investigations. The main results in 1998 were: - cod, haddock and to some extent Greenland halibut were not sufficiently covered due to very limted admittance to Russian EEZ. - all indices as well as lengths and weights at age have been adjusted based on data for Norwegian EEZ 1 total area in 1996, but the adjustments for cod and haddock are inaccurate because the proportions found in the Norwegian EEZ have varied much in recent years. - the abundance indices of 1-4 year old cod were above average or high, while the numbers of 5 year and older fish were lower than in recent years. - the abundance of 1 year old haddock was low, the indices for 2-6 year olds were below average, while the abundances of 7-8 year olds were arnong the highest in the time series - both cod and haddock had low length and weight at age, low weight increment but more normal condition factors. - the indices for S. marinus were a little higher than in 1997 and at or slightly above average leve1 in the time series, while for S. mentella the indices were lower than in in 1997 and below average. - the total abundance index of Greenland halibut increased a little from 1997 to 1998, but recmitment seems weak and the abundances of young age groups (c 5 years) are still very low. NORSK SAMMENDRAG:Eit kombinert akustikk- og botntråltokt med sikte på å framskaffa indeksar for talet på fisk og data for individuell lengde og vekt av kvar aldersgruppe av viktige botnfiskarter er gjennomført kvar vinter (4-6 veker i januar - mars) sidan 1981 i Barentshavet. Hovudinnsatsen er retta mot ungfiskbestandane av torsk og hyse, men i seinare år er slike indeksar også utarbeidde for uerartene og blåkveite. Sidan 1993 er undersøkingsområdet utvida mot nord og aust for å få ei fullstendig dekking av den isfrie delen av utbreiingsområdet til dei yngste årsklassane av torsk. Vinteren 1997 vart bene den norske delen av Barentshavet dekka, medan ein i 1998 fekk tilgang til ein liten del av russisk sone. Resultata for 1998 viser: - torsk, hyse og i nokon grad blåkveite vart mangelfullt dekka p.g.a. stengt russisk sone - alle totalindeksar samt lengder og vekter ved alder er justerte baserte på data for norsk sone 1 totalområdet i 1996, men justeringane for torsk og hyse er usikre sidan den delen av bestandane som er funne i norsk sone har variert ein god del dei siste åra. - 1-4 gruppe indeksane av torsk er over middels og til dels sterke, tala for 5 år og eldre fisk er kraftig redusert og lågare enn på fleire år. - l-gruppe indeksen av hyse er svak, 2-6 gruppa er under middels medan det er bra med 6-7 åringar. - både torsk og hyse har låg lengde og vekt ved alder, låg tilvekst, men bra kondisjon. - begge indeksane for vanleg uer er litt hergare enn i 1997 og på middels nivå eller litt over i tidsserien. - for snabeluer er indeksane under fjorårsnivået og godt under middels i tidsserien. - totalindeksen (botntrål) for blåkveite auka litt frå 1997 til 1998, men det er berre svake teikn til rekruttering og lite fisk mindre enn 40 cm