Cod movement ecology in a warming world: Circumpolar arctic gadids

Abstract

Understanding fish movement in the Arctic is paramount during the current era of rapidly warming seas, receding sea ice and associated shifting species distributions and fishing effort. We synthesized the literature and identified key knowledge gaps on the movement ecology of Arctic cod (Boreogadus saida) and Polar/Ice cod (Arctogadus glacialis, both Gadidae) in the context of climate change. Standardized web-based English-language literature searches yielded 51 articles directly relevant and 122 indirectly relevant for the movement ecology of these species combined. Most articles were primarily relevant to B. saida (85% of total filtered articles), occurred during open water season (49/38%) with focus on distribution (32/22%), predators (30/22%), seasonal spawning/feeding movements (22/19%), sea ice association (22/26%), climate change (20/15%) and vertical movements (17/19%) with few focused on horizontal dynamics (3/0%; B. saida/A. glacialis, respectively). Disproportionate data resolution has resulted in greater predictive power of movement models for the European (29% of articles) and North American (86%) Arctic regions relative to the logistically challenging Central Arctic Ocean and Russian-Siberian Arctic shelves (both 7%). The movements of circumpolar Arctic gadids are dependent on complex dynamics that include regional currents, the longevity of ice-flows and polynyas, water stratification and coastal hydrology. Dependence on these interactive and often co-dependent processes highlights major pathways and barriers to movement and distribution at higher latitudes. Despite a recent increase in impactful research, there is a critical need for more direct research on circumpolar gadid movements to aid understanding of climate change impacts on Arctic ecosystems and fisheries.

Decadal migration phenology of a long-lived Arctic icon keeps pace with climate change

“…Greenland halibut ( Reinhardtius hippoglossoides ) migration to the offshore is also timed with ice formation ( 58 ), which may suggest that their migration phenology will similarly shift. How Arctic cod ( Boreogadus saida ) in the Eclipse Sound region will respond in the short term to climate shifts is not directly known ( 59 ), but a predicted climate-induced increase in cod biomass could result in higher resource availability in the summer. Prey species community composition is also being modified through northward shifts of temperate zooplankton and fish species, which are often of lower caloric value ( 60 ).…”

Fish in Kongsfjorden under the influence of climate warming

“…Given that in 2013 and 2022, data were collected during the "day" (08.45 -17.00 UTC) and "night" (00.10 -04.00 UTC) periods (Table 1), respectively, the second hypothesis proposes an interpretation of the results, taking into account the possible Diel Vertical Migration (DVM) of medium-size fish. Previous studies (Falk-Petersen et al, 2008;Last et al, 2020;Pettitt-Wade et al, 2021) have confirmed that biological clocks of marine organisms are important for shaping their daily activities at high latitudes, and there are some confirmations that organisms could perform DVM in the Arctic during the Polar Night or Polar Day.…”

Year-Round Dive Characteristics of Male Beluga Whales From the Eastern Beaufort Sea Population Indicate Seasonal Shifts in Foraging Strategies

“…Eastern Beaufort Sea belugas occupied diverse bathymetric habitats during fall, from deep waters of the Arctic Basin to the shallow Chukchi Sea, explaining large variation in dive behavior observed during this period (Figures 4, 8). Benthic diving to >800 m along the Beaufort, Chukchi, and East Siberian slopes (Figure 4) could represent feeding on Greenland halibut, which is found in greatest abundance at seafloor depths ≥500 m (Majewski et al, 2017), when Arctic cod in the Beaufort Sea redistribute into the mesopelagic layer in fall (Geoffroy et al, 2016;Pettitt-Wade et al, 2021). EBS belugas principally made two deep dive types in the Arctic Basin: deeper Deep Pelagic V and shallower Deep Pelagic W dives (Figures 8, 9C), suggesting that two different depth layers were targeted at ∼100-300 m and >500 m (Table 2).…”