Production of fish larvae and their prey in subarctic southeastern Hudson Bay

Abstract

In the ice-covered southeastern Hudson Bay (northern QuCbec, Canada), marine fish exhibited 2 distinct reproduction strategies. Sand lance Amrnodytes sp. and Arctic cod Boreogadus saida produced large numbers of small larvae that hatched before the ice break-up when the abundance of prey (copepod eggs and nauplii) was low. Feeding incidence was low and the larvae fed on relatively small prey. A morphometric index of condition suggested that the 2 species suffered from starvation at first feeding. This critical period was approximately synchronized with peak abundance of prey, possibly an adaptation to minimize starvation mortality. Shchaeidae and Cottidae produced small numbers of large larvae that fed efficiently on relatively large prey before yolk resorption. These larvae emerged after the ice break-up, when phytoplankton production was well under way and prey were abundant. Interannual variations in the timing between first feeding and the production of prey could influence recruitment in sand lance and Arctic cod but are unlikely to affect the early survival of Stichaeidae and Cottidae.

Observations and Predictions of Arctic Climatic Change: Potential Effects on Marine Mammals

“…Many species of copepods (Calanus glacialis, Pseudocalanus spp., Oithona similus) reproduce under the ice before the phytoplankton bloom and feed on sedimenting ice algae (Drolet et al, 1991). Large Calanus, together with amphipods, constitute the bulk of the diet of arctic cod (Bradstreet et al, 1986).…”

“…Large Calanus, together with amphipods, constitute the bulk of the diet of arctic cod (Bradstreet et al, 1986). In turn, the larvae of arctic cod (B. saida) depend on the production of ice algae to support the productivity cycles of copepods, which supply the copepod eggs and nauplii upon which fish larvae feed (Drolet et al, 1991). Therefore, the timing of the phytoplankton bloom, driven by the breakup and melting of ice, is critical to the immediate success of firstfeeding larvae of arctic cod.…”

The match/mismatch hypothesis and the feeding success of fish larvae in ice-covered southeastern Hudson Bay

“…Slow growth due to reduced f e e d~n g success would lengthen the period of vulnerability of fish larvae to predators, thus increasing total cumulative mortality in the first months of life (Cushing & Harris 1973, Shepherd & Cushing 1980, Anderson 1988, Cushing 1990, Cushing & Horwood 1994 The timing between the occurrence of fish larvae and their prey could be particularly critical in seasonally ice-covered arctic and subarctic seas where the season of biological production is short (Cushing 1975, Drolet et al 1991. In subarctic Hudson Bay, Canada, the larvae of 14 fish species occur before the break-up of the winter ice cover (Ponton et al 1993).…”

“…Arctic cod Boreogadus saida and sand lance Ammodytes sp., which numerically dominate the ichthyoplankton assemblage, are the earliest species to emerge. The larvae first appear at the onset of biological production in early May, when ice algae start to grow at the ice-water interface (Drolet et al 1991, Ponton et al 1993.…”

The ecology of gadid fishes in the circumpolar Arctic with a special emphasis on the polar cod (Boreogadus saida)

“…The polar cod is the most abundant Arctic gadid and occupies a wide variety of habitats including nearshore waters, semi-enclosed bays, Arctic and subarctic shelves, continental slope regions and the Central Arctic Basin (Drolet et al 1991;Michaud et al 1996;Hop et al 1997;Norcross et al 2010;Logerwell et al 2015;Mecklenburg and Steinke 2015;David et al 2016;Kessel et al 2016). Relatively large abundances occur in the western Beaufort Sea (Benoit et al 2008) and in the eastern and northern Barents Sea, where they have supported a modest-sized fishery of up to 50,000 t in recent decades (Hop and Gjø-saeter 2013;McBride et al 2014).…”