Widespread phenological shifts with temperature in Alaska’s marine fishes

Changes in the timing of fish spawning and early life stage development can affect the temporal match or mismatch of larvae with production of preferred prey as well as their availability to predators, with potential consequences for recruitment success, food-web dynamics, and fisheries. Using >370,000 observations from over four decades of spring ichthyoplankton surveys in the Gulf of Alaska and Bering Sea, we investigated long-term changes in the phenology of 29 fish species, including commercially important taxa such as Pacific cod, walleye pollock, and Pacific halibut. Larval size on a standardized date (size-at-date) was used as a proxy for larval developmental timing in spring, and reflects a combination of hatch timing (larval age), growth, and mortality. Spatiotemporal generalized linear mixed models were used to account for variable sampling effort in space and time in order to isolate long-term trends and thermal effects on larval size. For a majority of species, interannua...,
Survey Data
Ichthyoplankton surveys in Alaska’s waters have been conducted by the National Oceanic and Atmospheric Administration’s Alaska Fisheries Science Center (NOAA AFSC) and partners since the 1970s, becoming more frequent in the 1980s (GOA) and 1990s (EBS). At each survey station, paired 60-cm bongo nets were towed obliquely from a depth of at least 100 m, or 10 m off the bottom in shallower waters. Net mesh sizes were either 333-µm or 505-µm. For each tow, the contents of one net were preserved in 5% formalin and later sorted and identified to the lowest taxonomic level possible at the Plankton Sorting and Identification Center in Szczecin, Poland. Up to 50 larvae of each taxa from each tow were measured for standard length after preservation. Species identifications were verified by expert taxonomists at NOAA AFSC. Survey coverage and timing has varied over the years due to differing survey objectives and ship time allocations, although many earlier surveys were specifically t..., # Widespread phenological shifts with temperature in Alaska’s marine fishes

Dataset DOI: [10.5061/dryad.2280gb66b](https://doi.org/10.5061/dryad.2280gb66b)

## Description of the data and file structure

#### Survey Data

Ichthyoplankton surveys in Alaska’s waters have been conducted by the National Oceanic and Atmospheric Administration’s Alaska Fisheries Science Center (NOAA AFSC) and partners since the 1970s, becoming more frequent in the 1980s (GOA) and 1990s (EBS). At each survey station, paired 60-cm bongo nets were towed obliquely from a depth of at least 100 m, or 10 m off the bottom in shallower waters. Net mesh sizes were either 333-µm or 505-µm. For each tow, the contents of one net were preserved in 5% formalin and later sorted and identified to the lowest taxonomic level possible at the Plankton Sorting and Identification Center in Szczecin, Poland. Up to 50 larvae of each taxa from each tow were measured for standard length after preservation. Species identifications were...,