Effects of climate and spawning stock structure on the spatial distribution of Northeast Arctic cod larvae

Abstract

The spatial distribution of fish early life stages can impact recruitment at later stages and affect population size and resilience. Northeast Arctic (NEA) cod spawning occurs along the Norwegian coast. Eggs, larvae, and pelagic juveniles drift near-surface towards the Barents Sea nursery area. In this study, a 35-year long time series of NEA cod larvae data was analysed in combination with factors that potentially may affect the distribution of eggs and larvae. These factors included biological aspects of the spawning stock, and environmental variables, such as water temperature, wind, ocean current, and prey abundance. Our aim was to shed light on how these factors influence larval abundance and distribution and how larval abundance and distribution influenced recruitment at age 3. We found that biomass and mean weight of the spawners were positively associated with larval abundance and that a high liver condition index of the spawners was associated with a north-easterly distribution of the larvae. The environmental variables showed generally weak or no correlations with abundance or distribution of larvae. Lastly, we found significant association between larval abundance and year-class abundance at age 3, while the spatial distribution metrics of the larvae, i.e. distribution extent, mean longitude, and mean latitude, showed no significant association with future year-class abundance.

Interannual variation in the coastal distribution of a juvenile gadid in the northeast Pacific Ocean: The relevance of wind and effect on recruitment

“…On the Great Barrier Reef over 23 years, wind direction was a significant factor in strong recruitment events of snapper ( Lutjanus carponotatus ) (Schlaefer et al., 2018). For cod ( Gadus morhua ), retention of eggs in a Newfoundland fjord was related to wind direction and speed (Knickle & Rose, 2010) while retention of larvae along the Norwegian coast was explained by downwelling‐favorable southwesterly wind, which is common during positive phases of the North Atlantic Oscillation (Endo et al., 2020). In the Bering Sea, wind‐driven transport direction of walleye pollock early life stages varied with climate phases and is hypothesized to affect spatial overlap of juveniles and adults thereby affecting cannibalism (Wespestad, Fritz, Ingraham, & Megrey, 2000).…”

“…One relevant component of meteorology is wind. As a driver of ocean circulation, wind (speed, direction, and duration) has most recently been associated with the recruitment of snapper (Lutjanus carponotatus) larvae to coral reefs (Schlaefer, Wolanksi, Lambrechts, & Kingsford, 2018) and retention of cod (Gadus morhua) larvae along the Norwegian coast (Endo, Vikebø, Yaragina, Hjøllo, & Stige, 2020).…”

“…One relevant component of meteorology is wind. As a driver of ocean circulation, wind (speed, direction, and duration) has most recently been associated with the recruitment of snapper ( Lutjanus carponotatus ) larvae to coral reefs (Schlaefer, Wolanksi, Lambrechts, & Kingsford, 2018) and retention of cod ( Gadus morhua ) larvae along the Norwegian coast (Endo, Vikebø, Yaragina, Hjøllo, & Stige, 2020). In the Gulf of Alaska (GOA), wind was related to survival and transport of larval walleye pollock ( Gadus chalcogrammus ) (Bailey, Bond, & Stabeno, 1999; Bailey, Canino, Napp, Spring, & Brown, 1995).…”

Long‐term variability in spawning stock age structure influences climate–recruitment link for Barents Sea cod

“…The Barents Sea cod spawn in March–May in patchy areas off mid and northern Norway, from Møre at 63°N to Finnmark at 71°N (Ellertsen et al, 1989 ; Endo et al, 2021 ; Figure 1 ). During the following ca 5‐month pelagic eggs, larvae and early juveniles follow the currents towards the north and east and are spread all over the southern Barents Sea and south‐west of Spitsbergen, 600–1200 km from their spawning ground, when they settle towards the bottom as 0‐group.…”