scholarly journals Occurrence of anisakid nematodes in Atlantic cod (Gadus morhua) and Greenland cod (Gadus ogac), West Greenland

2010 ◽  
Vol 55 (1) ◽  
Author(s):  
Kim Mouritsen ◽  
Rasmus Hedeholm ◽  
Henriette Schack ◽  
Lone Møller ◽  
Marie Storr-Paulsen ◽  
...  
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Infection Intensity ◽  
Stomach Contents ◽  
Nematode Species ◽  
Commercial Fishing ◽  
Opposite Pattern ◽  
West Greenland ◽  
Pcr Rflp ◽  
Anisakid Nematodes

AbstractAnisakid nematodes commonly infect gadids, and are of economic and aesthetic importance to the commercial fishing industry in Greenland as some species are pathogenic to humans. However, very little is known about the occurrence of these parasites and their impact on the hosts in Greenland waters. During a survey in 2005, stomach sample of 227 Atlantic cod (Gadus morhua) and 64 Greenland cod (Gadus ogac) was collected in Godthaab and Sisimiut fiord systems in West Greenland waters. All cod were dissected for stomach contents and anisakid nematodes were removed from the visceral cavity. Third stage larvae (L3) of three anisakid species were found, including Contracaecum osculatum (Rudolphi, 1802), Anisakis simplex (Rudolphi, 1809) and Hysterothylacium aduncum (Rudolphi, 1802). Molecular identification by PCR-RFLP indicated the presence of A. simplex s.s. and the sibling species C. osculatum B and C. The prevalence of infection by C. osculatum was higher in Greenland cod (84.3%) than in Atlantic cod (73.9%) whereas the prevalence of A. simplex showed an opposite pattern (Greenland cod 8.3%; Atlantic cod 24.2%). Only one G. morhua (1.0%) was infected by H. aduncum. No gender specific difference in both nematode species regarding prevalence of infection and mean infection intensity was evident, and there was no relationship between fish condition and the intensity of nematode infections. Standardised for size, capelin-eating cod were in better condition and more heavily infected than fish subsisting on alternative prey at the point of collection. Hence, nematode infections in the two gadids seem governed in part by feeding behaviour, and capelin appears a significant source of larval anisakids.

Chapter 3 Effects of Climate Change and Commercial Fishing on Atlantic Cod Gadus morhua

2009 ◽  
pp. 213-273 ◽  
Author(s):  
Nova Mieszkowska ◽  
Martin J. Genner ◽  
Stephen J. Hawkins ◽  
David W. Sims
Keyword(s):  
Climate Change ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Commercial Fishing

Occurrence and distribution of parasites in relation to food components of grey gurnard, Eutrigla gurnardus (L.) (Teleostei: Scorpaeniformes), off the Shetland Islands

2014 ◽  
Vol 43 (3) ◽  
Author(s):  
Ewa Sobecka ◽  
Beata Więcaszek ◽  
Ewa Łuczak ◽  
Artur Antoszek
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Stomach Contents ◽  
Food Composition ◽  
Parasite Fauna ◽  
Intermediate Hosts ◽  
Shetland Islands ◽  
Grey Gurnard ◽  
By Catch ◽  
First Time

AbstractThe research was conducted on the parasite fauna and food composition of Eutrigla gurnardus caught as by-catch in commercial catches of the Atlantic cod Gadus morhua near the Shetland Islands. Thirteen species and two genera of pathogens were identified, including six species and one genus recorded for the first time in this host. Copepoda — Euphausiacea dominated in the stomach contents (they are also the intermediate hosts for most of the parasites found), while Gadidae dominated among the fish. A checklist of E. gurnardus parasites is included.

Energetic consequences of reproduction in Atlantic cod (Gadus morhua) in relation to spawning level of somatic energy reserves

2000 ◽  
Vol 57 (4) ◽  
pp. 815-825 ◽  
Author(s):  
Yvan Lambert ◽  
Jean-Denis Dutil
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Good Condition ◽  
Reproductive Potential ◽  
Reproductive Investment ◽  
Energy Losses ◽  
Commercial Fishing ◽  
Energy Reserves ◽  
Poor Condition ◽  
Somatic Energy

The influence of a lower condition on reproductive investment, somatic energy losses, and postspawning condition of Atlantic cod (Gadus morhua) was examined under the hypothesis that females, in response to lower available energy reserves, would reduce reproductive investment in order to limit somatic energy losses. Laboratory experiments revealed that female cod with high prespawning condition factors ended reproduction in better condition than females with low prespawning condition factors. Fecundity and total egg dry weight were significantly lower in poor-condition females. The loss in somatic mass and energy in these poor-condition females was nevertheless higher, in relative terms, than the losses experienced by females in good condition. Consequently, energy reserves invested in reproduction by poor-condition females increase their risk of mortality. In the northern Gulf of St. Lawrence during the early 1990s, reproductive females had lower fecundities and were in worse prespawning and postspawning condition. The condition of spent females suggested a greater impact of changes in environmental conditions on adult than on immature cod. Reproductive potential and possibly recruitment may have suffered from that situation and could have contributed to the failure of that stock to recover despite the moratorium on commercial fishing.

Why the Atlantic cod (Gadus morhua) stock off eastern Nova Scotia has not recovered

2001 ◽  
Vol 58 (8) ◽  
pp. 1613-1623 ◽  
Author(s):  
Caihong Fu ◽  
Robert Mohn ◽  
L Paul Fanning
Keyword(s):  
Nova Scotia ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Commercial Fishing ◽  
Sudden Increase ◽  
Annual Variations ◽  
Structured Population ◽  
Population Dynamics Model ◽  
Structured Population Dynamics ◽  
Age Structured

An age-structured population dynamics model, incorporating interactions between Atlantic cod (Gadus morhua), the fishery, and the grey seal (Halichoerus grypus) population, was applied to the cod stock off eastern Nova Scotia (Northwest Atlantic Fisheries Organization Divisions 4Vs and 4W, commonly abbreviated to 4VsW), a stock that has dramatically declined since the late 1980s. Mortality was modeled as having three components: fishing mortality (F), seal predation (Mp), and all other sources of natural mortality (M). Specifically, M was assumed to be distinct for immature cod (ages 1–4; Mi) and mature cod (age 5 and older; Mm), and respective annual variations were estimated. Parameters estimated also included recruitment (cod abundance at age 1; R), F, and Mp. Based on our estimates of F, Mp, and M, it is unlikely that the collapse of the 4VsW cod stock can be attributed to a sudden increase in M; fishing appears to have been the primary cause for the stock's decline. However, after the moratorium on commercial fishing in 1993, increasing Mp and Mm and low R may have contributed to the failure of the 4VsW cod stock to recover.

scholarly journals Distribution and abundance of sealworm (Pseudoterranova decipiens) and other anisakid nematodes in fish and seals in the Gulf of St. Lawrence: potential importance of climatic conditions

2001 ◽  
Vol 3 ◽  
pp. 113 ◽  
Author(s):  
David J Marcogliese
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Climatic Conditions ◽  
Pseudoterranova Decipiens ◽  
Nematode Abundance ◽  
Contracaecum Osculatum ◽  
Myoxocephalus Scorpius ◽  
Longhorn Sculpin ◽  
Anisakid Nematodes ◽  
Seal Diet

Prevalence and abundance of sealworm (Pseudoterranova decipiens) and other anisakid nematodes were determined in a variety of fishes from the Gulf of St. Lawrence in 1990 and 1992. Sealworm abundance and prevalence were also determined in three species of seals in the Gulf between 1988 and 1992. Atlantic cod (Gadus morhua) and shorthorn (Myoxocephalus scorpius) and longhorn sculpin (M. octodecemspinosus) were the fishes most heavily infected with sealworm. Grey seals(Halichoerus grypus) proved to be the most important definitive hosts for sealworm in the Gulf. Abundance of sealworm increased, whereas that of Anisakis simplex and contracaecine nematodes decreased, from north to south in the Gulf. Abundance of sealworm increased compared to earlier surveys in most areas of the Gulf, but decreased in both cod and grey seals during the course of this study. In contrast, abundance of Contracaecum osculatum and Phocascaris spp. in grey seals and cod continued to increase during the study period. Observed increases of nematodes are attributed to growing populations of grey seals (for sealworm) and harp seals (for Contracaecinea). Levels of A. simplex remained relatively constant between 1988 and 1992 in both grey seals and cod. There is no evidence suggesting that observed patterns in nematode abundance were due to changes in grey seal diet. Nor was there any evidence of competition between P. decipiens and C. osculatum in grey seals affecting either sealworm abundance or fecundity. The trends detected herein are attributed to climatic events in the Gulf of St. Lawrence, where water temperatures in the cold intermediate layer consistently decreased between 1986 and 1994. It is suggested that low temperatures inhibited development and hatching of sealworm eggs, but not those of C. osculatum.

scholarly journals Shallow-Water Scavengers of Polar Night and Day – An Arctic Time-Lapse Photography Study

2021 ◽  
Vol 8 ◽  
Author(s):  
Piotr Balazy ◽  
Marti J. Anderson ◽  
Maciej Chelchowski ◽  
Maria Włodarska-Kowalczuk ◽  
Piotr Kuklinski ◽  
...  
Keyword(s):  
Shallow Water ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Time Lapse ◽  
Seasonal Effects ◽  
Polar Night ◽  
Opposite Pattern ◽  
Svalbard Archipelago ◽  
Scavenger Activity ◽  
Night And Day

Until recently, polar night constituted truly a “mare incognitum” of our times. Yet, the first records from this very little-explored period showcased a surprisingly rich and active ecosystem. This investigation aims to reveal the level of scavenger activity during both Arctic polar night and day. It compares the shallow-water scavenging fauna observed during two contrasting seasons (winter vs. summer) in a high Arctic fjord (Kongsfjorden, 79° N, Spitsbergen, Svalbard Archipelago). In each of January and July 2015, two different bait types – Atlantic cod (Gadus morhua) and a bird carcass (chicken meat) were deployed at a depth of 12 m. Fauna were monitored remotely using time-lapse cameras equipped with bait traps, with photographs taken every 15 min over a period of 4 days. Thirty taxa were recorded at baits, dominated by lysianassid amphipods (Onisimus sp. 88%, Anonyx sp. 2%, but only during winter), and buccinid gastropods (B. undatum 5%, B. glaciale 1%, Buccinum sp. 3%, in both seasons). In most cases, buccinids were the first animals to appear at bait. The total number of recorded taxa, mean species richness per sampling unit, total abundance and associations among taxa were higher, on average, in winter than in summer deployments, while Pielou’s evenness index showed the opposite pattern. Scavenger assemblages differed significantly between the two seasons and also in response to the two different bait types, with seasonal effects being strongest. Contrary to expectations, bait consumption rates differed very little between the two seasons, being slow in general and only slightly faster in summer (0.05 g of cod bait consumed in 1 min) compared to winter (0.04 g min–1), yielding novel insights into ecological interactions and functions in shallow marine ecosystems during Arctic polar nights.

scholarly journals Assessing changes in age and size at maturation in collapsing populations of Atlantic cod (Gadus morhua)

2005 ◽  
Vol 62 (4) ◽  
pp. 811-823 ◽  
Author(s):  
Esben Moland Olsen ◽  
George R Lilly ◽  
Mikko Heino ◽  
M Joanne Morgan ◽  
John Brattey ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Life Histories ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Reference Points ◽  
Reaction Norms ◽  
Commercial Fishing ◽  
Evolutionary Changes ◽  
Survival And Growth ◽  
Maturation Age

By estimating probabilistic reaction norms for age and size at maturation, we show that maturation schedules of Atlantic cod (Gadus morhua) off Labrador and Newfoundland shifted toward earlier ages and smaller sizes during the late 1980s and early 1990s, when these populations underwent a severe collapse in biomass and subsequently were closed for directed commercial fishing. We also demonstrate that this trend towards maturation at younger ages and smaller sizes is halted and even shows signs of reversal during the closure of the fisheries. In addition, our analysis reveals that males tend to mature earlier and at a smaller size than females and that maturation age and size decrease with increasing latitude. Importantly, the maturation reaction norms presented here are robust to variation in survival and growth (through phenotypic plasticity) and are thus strongly indicative of rapid evolutionary changes in cod maturation as well as of spatial and sex-specific genetic variation. We therefore suggest that maturation reaction norms can provide helpful reference points for managing harvested populations with evolving life histories.

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.

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