The trophic ecology of Atlantic cod: insights from tri‐monthly, localized scales of sampling

Abstract

The meso-scale trophic dynamics of cod Gadus morhua were examined based upon tri-monthly stomach sample collections from a nearshore, localized (c. 800 km 2 ) region off Cape Cod, Massachusetts, U.S.A. The major objective for this work was to relate any changes in cod diet and amount of food eaten to seasonal variations in prey availability, water temperature and spawning at a spatial scale between broad-scale and laboratory studies. Results suggested that the type and amount of food eaten by cod was generally consistent throughout a year and repeatable across years. Cod feeding was marked by two periods of increased feeding, corresponding to the arrival of small pelagic fishes in the area. This pelagic migration and subsequent increased feeding by cod occurred during important periods in the life history of cod (e.g. spawning and overwintering). Similar annual patterns in food consumption and diet composition were remarkably consistent over the 2Á5 years of the project, suggesting important feeding periods for cod that correspond to environmental and biological events. The diet of cod was composed primarily of several species of forage fishes [e.g. herrings (predominantly Atlantic herring Clupea harengus), sand lance Ammodytes sp. and Atlantic mackerel Scomber scombrus], ophiuroids, Cancer sp. crabs and other small crustaceans. It was inferred that cod exhibited a maintenance diet on local forage fishes and benthic macroinvertebrates, augmenting their diet by seasonally gorge feeding upon migrating pelagic species.Journal compilation # 2007 The Fisheries Society of the British Isles No claim to original US government works

Diets and Stable Isotope Derived Food Web Structure of Fishes from the Inshore Gulf of Maine

“…McDermott et al (2015) used trawl gear in 2010-2011 in the Midcoast region to address similar questions regarding river herring as groundfish prey, finding that the odds of encountering river herring in groundfish stomachs was highest closest to the rivers where river herring spawn. Smith et al (2007) noted a similar seasonal pulse pattern of fish prey in cod diets.…”

“…Stomach content analysis of groundfish from the Gulf of Maine (Garrison and Link 2000;Link et al 2009;Smith et al 2007) and nearshore waters of Midcoast Maine (McDermott et al 2015) have identified river herring as likely important to groundfish feeding behavior. These authors and others (Lake et al 2012;Saunders et al 2006) make strong and compelling arguments for restoring anadromous fish spawning habitat, particularly through dam removal, as a means of altering the decline of groundfish species.…”

Spawning Dynamics and Associated Management Implications for Atlantic Cod

“…Tagging studies have used angling techniques with feather hooks and jigs to capture spawning Atlantic Cod (e.g., Robichaud and Rose 2003;Dean et al 2012), which is indicative of a response to foraging stimuli. Feeding by spawning Atlantic Cod can also be greater than nonspawning fish or juveniles in some instances (Krumsick and Rose 2012) but appears to be more opportunistic because feeding has been observed to be more extensive postspawning (Link and Burnett 2001;Smith et al 2007).…”

Quantifying alosine prey in the diets of marine piscivores in the Gulf of Maine

“…As a generalist feeder, it is not unreasonable to infer that G . morhua might consume alosine prey when encountered (Link & Garrison, ; Smith et al , ; Link et al , ). Ames & Lichter () further hypothesize that G .…”