Growth and feeding habits of grey seals (Halichoerus grypus) in the northwestern Gulf of St. Lawrence, Canada

1992 ◽  
Vol 70 (8) ◽  
pp. 1604-1613 ◽  
Author(s):  
D. J. Murie ◽  
D. M. Lavigne
Keyword(s):  
Fish Species ◽  
Gadus Morhua ◽  
Feeding Habits ◽  
Clupea Harengus ◽  
Halichoerus Grypus ◽  
Capelin Mallotus Villosus ◽  
Gross Energy ◽  
Clupea Harengus Harengus ◽  
Feeding Bout ◽  
Differential Digestion

Growth and feeding habits were determined for 82 grey seals (Halichoerus grypus) collected in the northwestern Gulf of St. Lawrence, Canada, between 3 July and 6 December 1983. Male grey seals reached an asymptotic standard length of 242 cm, whereas females attained a length of 201 cm. Most (96%) females 175 cm or longer and 5 years of age or older were pregnant. A larger proportion of grey seal stomachs contained food items in July than in the other months sampled, regardless of sex or maturity status. The diet consisted primarily of cod (Gadus morhua), herring (Clupea harengus harengus), and capelin (Mallotus villosus), which together contributed 72% of the wet mass and 76% of the gross energy of all the prey consumed. Invertebrates contributed negligible mass or gross energy to the diet. Grey seals primarily consumed fish ≤30 cm in length and ate only one or two different fish species during any one feeding bout. Based on our stomach content analyses, the food consumed daily by adult male and female grey seals provided an average gross energy of 3628 and 2925 kcal (1 kcal = 4.18 kJ), respectively, which is consistent with daily energy requirements estimated using bioenergetic models. However, the large percentage of empty stomachs (50%), together with differential digestion of fish species, suggests that grey seals may not feed every day.

Interactions multispécifiques: répartition spatio-temporelle des larves de capelan (Mallotus villosus), d'éperlan (Osmerus mordax) et de hareng de l'Atlantique (Clupea harengus harengus) an sein de la communauté planctonique de l'estuaire moyen du Saint-Laurent

1982 ◽  
Vol 39 (8) ◽  
pp. 1164-1174 ◽  
Author(s):  
R. Courtois ◽  
M. Simoneau ◽  
J. J. Dodson
Keyword(s):  
Fish Larvae ◽  
Clupea Harengus ◽  
Temporal Organization ◽  
Physical Factors ◽  
Osmerus Mordax ◽  
Mallotus Villosus ◽  
Saint Lawrence River ◽  
Capelin Mallotus Villosus ◽  
Clupea Harengus Harengus ◽  
Species Specific

The study of the spatial and temporal organization of the planktonic community of the middle estuary of the Saint Lawrence River revealed that fish larvae were distributed in such a way as to minimize interactions between species. Smelt (Osmerus mordax) larvae were distributed upstream whereas capelin (Mallotus villosus) and Atlantic herring (Clupea harengus harengus) larvae were found downstream in June 1979. Capelin larvae were more abundant at the surface (0–20 m) whereas herring larvae were concentrated in deeper waters (20–60 m). The ecological separation observed was maintained by multiple physical factors and appeared to be the consequence of species-specific reproductive strategies. The abundance of chaetognaths, euphausiids, and amphipods in deeper waters suggests that these forms could be important predators of fish larvae. Herring larvae may be particularly vulnerable because of their distribution in deep water. Capelin larvae which are very abundant in June could also be vulnerable to predation during the diurnal migrations of the macroplankton. Smelt larvae appear to be little affected by predation from these forms as a result of their distribution in fresher waters.

scholarly journals Direct and indirect effects of minke whale abundance on cod and herring fisheries: A scenario experiment for the Greater Barents Sea

2000 ◽  
Vol 2 ◽  
pp. 120 ◽  
Author(s):  
Tore Schweder ◽  
Gro S Hagen ◽  
Einar Hatlebakk
Keyword(s):  
Gadus Morhua ◽  
Barents Sea ◽  
Minke Whale ◽  
Clupea Harengus ◽  
Prey Abundance ◽  
Balaenoptera Acutorostrata ◽  
Time Step ◽  
Minke Whales ◽  
Spawning Stock ◽  
Capelin Mallotus Villosus

To study the pattern of interaction between minke whale (Balaenoptera acutorostrata) abundance and the main fisheries in the Greater Barents Sea, a simulation experiment was carried out. The population model involves 4 species interconnected in a food web: cod (Gadus morhua), capelin (Mallotus villosus), herring (Clupea harengus) and minke whales. Minke whales are preying on cod, capelin andherring; cod are preying on (young) cod, capelin and herring; herring in the Barents Sea are preying on capelin; while capelin is a bottom prey in the model. The consumption function for minke whales is non-linear in available prey abundance, and is estimated from stomach content data and prey abundance data. The model is dynamic, with a time step of one month, and there are two areas: the BarentsSea and the Norwegian Sea. Minke whale abundances are kept on fixed levels, while recruitment in fish is stochastic.Cod and herring fisheries are managed by quotas targeting fixed fishing mortalities, while capelin is managed with a view to allow the cod to have enough food and leaving a sufficient spawning stock of capelin. The model is simulated over a period of 100 years for a number of fixed levels of minke whaleabundance, and simulated catches of cod, herring and capelin are recorded.The experiment showed interactions between whale abundance and fish catches to be mainly linear. For cod catches, both the direct effect of whales consuming cod, and the indirect effect due to whales competing with cod for food and otherwise altering the ecosystem, are linear and of equal importance. The net effect on the herring fishery is of the same magnitude as the net effect on the cod fishery, witheach extra whale reducing the catches of both species by some 5 tonnes. These conclusions are conditional on the model and its parameterisation.

scholarly journals Trophic interactions affecting a key ecosystem component: a multistage analysis of the recruitment of the Barents Sea capelin (Mallotus villosus)

2010 ◽  
Vol 67 (9) ◽  
pp. 1363-1375 ◽  
Author(s):  
Dag Øystein Hjermann ◽  
Bjarte Bogstad ◽  
Gjert Endre Dingsør ◽  
Harald Gjøsæter ◽  
Geir Ottersen ◽  
...  
Keyword(s):  
Trophic Interactions ◽  
Gadus Morhua ◽  
Barents Sea ◽  
Clupea Harengus ◽  
Mallotus Villosus ◽  
The Barents Sea ◽  
Key Species ◽  
Capelin Mallotus Villosus ◽  
Ecosystem Component ◽  
Recruitment Stages

The Barents Sea stock of capelin ( Mallotus villosus ) has suffered three major collapses (>90% reduction) since 1985 due to recruitment failures. As capelin is a key species in the area, these population collapses have had major ecosystem consequences. By analysing data on spawner biomass and three recruitment stages (larvae, 0-group, and 1-year-olds), we suggest that much of the recruitment failures are caused by predation from herring ( Clupea harengus ) and 0-group and adult Northeast Arctic cod ( Gadus morhua ). Recruitment is furthermore positively correlated with sea temperatures in winter and spring. Harvesting of maturing capelin on their way to the spawning grounds reduced the abundance of larvae significantly, but this reduction to a large extent is compensated for later in life, as mortality is strongly density-dependent between the larval stage and age 1. Altogether, our study indicates a very high importance of trophic interactions, consistent with similar findings in other high-latitude marine ecosystems.

scholarly journals Low incidence of plastic ingestion among three fish species significant for human consumption on the island of Newfoundland, Canada

2019 ◽  
Author(s):  
Max Liboiron
Keyword(s):  
Atlantic Salmon ◽  
Fish Species ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Human Consumption ◽  
Cultural Importance ◽  
Capelin Mallotus Villosus ◽  
Food Fish ◽  
Low Incidence ◽  
Contamination Levels

This study reports the first baselines of plastic ingestion for three fish species that are common commercial and sustenance food fish in Newfoundland. Species collections occurred between 2015 and 2016 for Atlantic cod (Gadus morhua), Atlantic salmon (Salmo salar), and capelin (Mallotus villosus). The frequency of occurrence (%FO) of plastic ingestion for both Atlantic salmon (n = 69) and capelin (n = 350) was 0%. Of the 1010 Atlantic cod individuals collected over two years, 17 individuals had ingested plastics, a %FO of 1.68%. This is the only multi-year investigation of plastic ingestion in Atlantic cod for the Northwest Atlantic, and the first baseline of plastic ingestion in Atlantic salmon and capelin on the island of Newfoundland. Considering the ecological, economic, and cultural importance of these fish species, this study is the beginning of a longitudinal study of plastic ingestion to detect any future changes in contamination levels.

scholarly journals Climate, zooplankton, and pelagic fish growth in the central Baltic Sea

2005 ◽  
Vol 62 (7) ◽  
pp. 1270-1280 ◽  
Author(s):  
Christian Möllmann ◽  
Georgs Kornilovs ◽  
Marina Fetter ◽  
Friedrich W. Köster
Keyword(s):  
Baltic Sea ◽  
Fish Species ◽  
Gadus Morhua ◽  
Principal Component ◽  
Pelagic Fish ◽  
Clupea Harengus ◽  
Fish Growth ◽  
Mesozooplankton Community ◽  
Temora Longicornis ◽  
Average Water

Abstract Oceanographic conditions in the brackish central Baltic Sea are strongly linked to atmospheric forcing and the unusual period of persistently strong westerlies that, since the late 1980s, have resulted in an increase in average water temperatures and decreasing salinity. These changes in temperature and salinity resulted in a change in the dominance of the mesozooplankton community from Pseudocalanus sp. to Temora longicornis and Acartia spp. Similar to the copepod community, the central Baltic fish community shifted from cod (Gadus morhua), dominant during the 1980s, to sprat (Sprattus sprattus), dominant during the 1990s. Further, the commercially important pelagic fish species herring (Clupea harengus) and sprat exhibited reductions in growth. Using Principal Component and Correlation Analyses we investigated the temporal variability in the importance of the food supply as well as competition on condition of central Baltic pelagic fish species. Our results indicate that herring condition results from a combined effect of changes in the food environment and increased competition with sprat, while sprat condition appeared to be primarily determined by intra-specific competition.

Diet of harp seals (Phoca groenlandica) in nearshore waters of the northwest Atlantic during 1990 – 1993

1995 ◽  
Vol 73 (10) ◽  
pp. 1805-1818 ◽  
Author(s):  
John W. Lawson ◽  
Garry B. Stenson ◽  
Dave G. McKinnon
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Stomach Contents ◽  
Clupea Harengus ◽  
Relative Importance ◽  
Northwest Atlantic ◽  
Arctic Cod ◽  
Diet Diversity ◽  
Phoca Groenlandica ◽  
Capelin Mallotus Villosus

The nearshore diet of northwest Atlantic harp seals (Phoca groenlandica) was determined by reconstructing the contents of 1167 prey-containing stomachs (78.3% of 1490) collected from 1990 to 1993. Although harp seals consumed at least 62 species, 6 accounted for most of the mass consumed and their relative importance varied by area. Based on percent wet mass, sculpins (Cottidae) and Arctic cod (Boreogadus saida) were the main components of the diet of older seals (> 1 year old) off Labrador, whereas Arctic cod and Atlantic herring (Clupea harengus) were the main prey of seals from northeastern Newfoundland. A more diverse diet was observed in seals taken off the west coast of Newfoundland, where capelin (Mallotus villosus), herring, Atlantic cod (Gadus morhua), redfish (Sebastes spp.), and Arctic cod were the main species. Redfish and Atlantic cod were important to seals along the south coast of Newfoundland. Eighty percent of fish consumed were less than 18 cm long, smaller than those taken by commercial fisheries. Pups (less than 1 year old) consumed fewer and smaller prey of a less varied assortment. Annual and seasonal variation in the diets was observed in the collection from northeastern Newfoundland. Arctic cod was the major prey consumed throughout the year by seals of all ages, although the relative importance of herring, capelin, and squid (Teuthoidea) increased during the summer. Invertebrates and capelin made up a greater proportion of the diet in 1992, owing to a decline in consumption of Arctic cod. This finding was associated with a decrease in the mass of stomach contents. Diet diversity did not change significantly over the study period.

scholarly journals Condition factor, heavy metals and polychlorinated biphenyls (PCBs) in the muscle of fishes harvested in, and imported into Lagos, Nigeria

2020 ◽  
Vol 5 (1) ◽  
pp. 38-46
Author(s):  
Oyelowo Oluwakemi ◽  
Awobajo Funmileyi ◽  
Samuel Titilola ◽  
Sogbesan Teniola ◽  
Fayiga Adewale ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Polychlorinated Biphenyls ◽  
Fish Species ◽  
Gadus Morhua ◽  
Polychlorinated Biphenyl ◽  
Condition Factor ◽  
Clupea Harengus ◽  
Adult Fish ◽  
Atlantic Mackerel ◽  
Permissible Limits

Fish is an important part of the human diet, are at the top of the aquatic food chain with a high propensity to accumulating contaminants like heavy metals and polychlorinated biphenyls (PCBs) which are toxic to humans.  The objective of this study was to evaluate the relationship between condition factor (physiologic wellbeing) of the fishes, PCBs, and heavy metal accumulation.Ten adult fish species three each of Chrysichthys nigrodigitatus, Trachinotus teraia, Liza dumerilli, Tilapia guieensis, Pseudotolithus elongatus, Pomadasys jubelini, Polydactylus quadrifilis, Caranx hippos, Sphyreana barracuda, Arius heudoloti,were acquired at Epe Lagoon. Ten adult fish species three each of Argentina silus, Gadus chalcogrammus, Gadus morhua, Atlantic mackerel, Micropogonias undulatus, Urophycis sp., Chrysichthys nigrodigitatus, Oreochromis niloticus, Clupea harengus, Trachurus trachurus, imported into Lagos were purchased. The fish species’ condition factor was determined. The heavy metals were determined using AAS while PCB level was determined using GC-MS. Iron, mercury, zinc, arsenic, nickel and copper levels correlated positively with the condition factor in the local fishes while in the imported fishes, cadmium, iron, zinc, nickel, copper and lead levels correlated positively to the condition factor. The levels of PCBs in both the local and imported fishes were non-detectable.  It is concluded that the lead, copper, arsenic, zinc, mercury and cadmium in both the imported and local fishes were within permissible limits compared with the FAO/WHO maximum permissible limits. The positive correlation of some heavy metals to the fishes’ condition factor infers that these metals might be altering physiologic activities in the fishes. Keywords: Condition factor; Heavy metals; Polychlorinated biphenyl; Fish

scholarly journals A note on stomach contents of minke whales (Balaenoptera acutorostrata) in Icelandic waters

2000 ◽  
Vol 2 ◽  
pp. 82 ◽  
Author(s):  
Jóhann Sigurjónsson ◽  
Anton Galan ◽  
Gísli A Víkingsson
Keyword(s):  
Food Habits ◽  
Gadus Morhua ◽  
Prey Species ◽  
Stomach Contents ◽  
Clupea Harengus ◽  
Balaenoptera Acutorostrata ◽  
Minke Whales ◽  
Capelin Mallotus Villosus ◽  
Available Information ◽  
Icelandic Waters

There is limited available information on food habits of minke whales (Balaenoptera acutorostrata) in coastal Iceland. Sixty-eight minke whales were examined for stomach contents; 51.5% contained fish only, 22.1 % krill (Euphausiacea) only, 25.0% fish and krill together, and one animal (l.5%) had no food remains in the stomach. The fish species identified were capelin (Mallotus villosus), sandeel (Ammodytidae), cod (Gadus morhua) and herring (Clupea harengus). Two species of krill were identified; Thysanoessa raschii and Meganyctiphanes norvegica. Sandeel was the dominant prey species in the western and southwestern areas, while capelin and krill were more frequently found in animals sampled in North Iceland.

Interpretation of otoliths in stomach content analyses of phocid seals: quantifying fish consumption

1986 ◽  
Vol 64 (5) ◽  
pp. 1152-1157 ◽  
Author(s):  
D. J. Murie ◽  
D. M. Lavigne
Keyword(s):  
Fish Consumption ◽  
Stomach Contents ◽  
Clupea Harengus ◽  
Halichoerus Grypus ◽  
Complete Disappearance ◽  
Atlantic Herring ◽  
Phoca Groenlandica ◽  
In The Wild ◽  
Phocid Seals ◽  
Clupea Harengus Harengus

Thirteen captive phocid seals (10 grey seals (Halichoerus grypus), 2 harp seals (Phoca groenlandica), and 1 ringed seal (P. hispida)) were fed Atlantic herring (Clupea harengus harengus) in experiments designed to examine the use of otoliths recovered in stomach contents to interpret food consumption of wild seals. The percentage of ingested otoliths recovered in the stomach contents decreased with the time elapsed after feeding; 100% of otoliths were recovered between 0 and 3 h after feeding and 0% were recovered by 12.9 h after feeding. Absence of otoliths in the large intestine of seals having fed 3 to 6 h previous indicated that unrecovered otoliths had been digested (i.e., a complete disappearance of whole otoliths) while in the stomach. A significant relationship was also evident between the state of digestion of a seal's stomach contents, as measured by the proportion of otoliths remaining in skull cases (skull-recovered otoliths), and the duration of time since it had fed. These relationships have potential application in the estimation of daily fish consumption of seals feeding in the wild.

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