Recent changes in the feeding of cod (Gadus morhua) off the Flemish Cap, Newfoundland 1989–1993

Casas, J. M.; Paz, J.

doi:10.1006/jmsc.1996.0096

Cited by 13 publications

(11 citation statements)

References 4 publications

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“…Casas and Paz (1996) and Powles (1958) observed an increase in diet diversity with increased age in cod from the Flemish Cap stock (NAFO 3M) and the Gulf of St Lawrence, respectively, but this was not observed in the present study. Our results indicate that mature cod had higher consumption of benthic or fish prey, primarily oil-rich fish such as capelin (M. villosus), herring (C. harengus), and sand lance (Ammodytes sp.)…”

Section: Diversitycontrasting

confidence: 51%

“…Much of the information on diet has been derived from stomach content studies, many limited to a single season within one or more years with assumptions of how this relates to annual consumption (Popova, 1963;Lilly and Fleming, 1981;Methven and Piatt, 1989;Casas and Paz, 1996;Gerasimova and Kiseleva, 1998;Adlerstein and Welleman, 2000). More comprehensive information on annual cod feeding has been obtained from studies utilizing data over entire years (Turuk, 1971;Daan, 1973;Klemetsen, 1982;Albikovskaya and Gerasimova, 1993;Schwalme and Chouinard, 1999;Mello and Rose, 2005;Link et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

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Atlantic cod (Gadus morhua) feed during spawning off Newfoundland and Labrador

Krumsick

Rose

2012

ICES Journal of Marine Science

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We test a current assumption that Atlantic cod (Gadus morhua) off Newfoundland and Labrador, Canada, do not feed during the protracted spawning season (March-September). Stomach contents were analysed from 10 473 cod from four Northwest Atlantic Fisheries Organization regions (2J, 3K, 3L, and 3Ps) over 9 years from which gonads were also analysed to determine sex and maturity status. Adult cod in spawning condition did feed in all regions, usually at rates equivalent to or even greater than non-spawning fish and juveniles. Both sexes fed during spawning, though females consumed lesser amounts. Regional differences were evident. The total fullness index was greater in the northern (2J) than the southern (3Ps) region, with no consistent differences between spawners and non-spawners. The most southerly region (3Ps) exhibited the greatest prey diversity, the northern region (2J) the least. Shrimp was the major diet item in the northern regions. Capelin, zooplankton, crab, and other fish increased in importance to the south. Differences in prey items between non-spawning and spawning individuals of both sexes were possibly related to spawning behaviour. Models using consumption rates should not assume that cod do not feed during the protracted spawning season in these waters.

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Section: Diversitycontrasting

confidence: 51%

Section: Introductionmentioning

confidence: 99%

Atlantic cod (Gadus morhua) feed during spawning off Newfoundland and Labrador

Krumsick

Rose

2012

ICES Journal of Marine Science

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“…Another possibility could be direct competition between the 2 species, as they both prey on benthic invertebrates such as small crustaceans (i.e. shrimp, crab) and molluscs (Waiwood & Majkowski 1984, Wieczorek & Hooper 1995, Casas & Paz 1996, Lovrich & Sainte-Marie 1997, Hanson & Chouinard 2002, Squires & Dawe 2003. The importance of top-down and bottom-up forces may vary between areas (Figs.…”

Section: Discussionmentioning

confidence: 99%

Top-down interactions and temperature control of snow crab abundance in the northwest Atlantic Ocean

Boudreau

Anderson²,

Worm³

2011

Mar. Ecol. Prog. Ser.

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In much of the northwest Atlantic Ocean, commercially important snow crab Chionoecetes opilio stocks have increased in abundance since the decline and collapse of major groundfish stocks such as Atlantic cod Gadus morhua. We examined 3 hypotheses to explain variation in the abundance of snow crabs across 10 regions: (1) climate control of both species, (2) top-down control of snow crab by cod and (3) bottom-up control of cod by snow crab. We tested these hypotheses by analyzing time series data of cod and crab abundance indices and temperature via meta-analysis of full and partial correlation coefficients. We found that temperature had an opposing effect on the 2 species: snow crab abundance was negatively correlated with temperature at 7 to 10 yr lags, whereas cod and temperature were positively related at 1 to 7 yr lags. Controlling for the effect of temperature, our meta-analysis revealed significant negative correlations of snow crab and cod abundance, with cod leading snow crab by up to a 5 yr lag. This suggests a top-down effect on older juvenile and subadult snow crab. We found no evidence of a bottom-up effect of snow crab on cod. Negative correlations between cod and crab abundance were observed both at the warmer and colder portions of their ranges. These results suggest that snow crab abundance is largely influenced by temperature during the early postsettlement years and becomes increasingly regulated by top-down mechanisms during the years approaching fishery recruitment. The method presented in this paper is generally useful to test ecological hypotheses from time series data, particularly where multiple causal mechanisms are suspected.

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“…the cod Gadus morhua is known to feed on benthic crustaceans to a large extent (e.g. Casas & Paz 1996, Gerasimova & Kiseleva 1998. However, considering the strong difference in the diet of the lesser black-backed gull between Juist and Amrum in 1997 and between Helgoland and Amrum in 2003 (Table 3) recorded in the present study, location would seem to play a decisive role in abundance of this species.…”

Section: Discussionmentioning

confidence: 99%

At-sea distribution and behaviour of a surface-feeding seabird, the lesser black-backed gull Larus fuscus, and its association with different prey

Schwemmer¹,

Garthe²

2005

Mar. Ecol. Prog. Ser.

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The lesser black-backed gull Larus fuscus is a typical surface-feeding seabird with a widespread, patchy distribution in the SE North Sea. During the 1990s, breeding numbers along the German North Sea coast increased exponentially. Analyses of a multiple-year data set revealed changes in the at-sea distribution that seemed to reflect an increase in the numbers of breeding birds. Detailed recordings of feeding and resting behaviour at sea revealed area utilisation by the lesser black-backed gull. Observations at sea and dietary analysis revealed that swimming crabs Liocarcinus spp. are a major dietary item of this gull species. This natural food source was primarily captured close to the shore; at longer distances from the coast the gulls mainly fed on other natural prey items or discarded fishes from trawlers and avoided competition with other breeding gull species. During July and August 1990 to 1995 L. fuscus abundance was significantly correlated with fishing effort, while in May and June there was no such correlation. Time of day was the main environmental variable influencing the gulls' flight activity and indicated an association between activity and availability of their major natural prey, swimming crabs. Distinct patterns and changes in the at-sea distribution and foraging behaviour of L. fuscus in the SE North Sea reflect anthropogenic and natural influences in their habitats.

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Recent changes in the feeding of cod (Gadus morhua) off the Flemish Cap, Newfoundland 1989–1993

Cited by 13 publications

References 4 publications

Atlantic cod (Gadus morhua) feed during spawning off Newfoundland and Labrador

Atlantic cod (Gadus morhua) feed during spawning off Newfoundland and Labrador

Top-down interactions and temperature control of snow crab abundance in the northwest Atlantic Ocean

At-sea distribution and behaviour of a surface-feeding seabird, the lesser black-backed gull Larus fuscus, and its association with different prey

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