Validation of pop-up satellite archival tags (PSATs) on Atlantic cod (Gadus morhua) in a Greenland fjord

Traditional tagging techniques are simple and cost-effective, but inferences require recaptures and data on movement/migration are limited to a start and end position at unpredictable intervals. Pop-up satellite archival tags (PSATs) offer other opportunities, as they provide positions at pre-programmed times and collect on-route data, which can be used to describe position, behavior, and habitat preferences. Species suitability should, however, be documented prior to large-scale studies using PSATs. We deployed PSATs on six relatively large (total length 84–125 cm) Atlantic cod (Gadus morhua) in inshore West Greenland waters. Three tags were physically recovered, providing high-resolution data on depth and temperature (readings every 3 s), while three tags did not report (recovery rate = 50 %). To evaluate the tag’s applicability on Atlantic cod, we made a detailed behavioral analysis by defining swimming behavior, occupied water types and depth phases, which were cross-evaluated in relation to depth, temperature and water stratification to identify behavioral patterns. Distinct and shared patterns in swimming behavior were evident and we found no signs of impaired swimming behavior except for an adaptation period lasting up to 39 h after release. Generally, the three cod were pelagic and preferred waters ranging 2–5 °C. When encountering colder water masses these were avoided. During late summer/early autumn, increased vertical activity could in some cases be linked to darkness and a high-activity event could be linked to possible predator avoidance. All combined, we conclude that PSATs are suitable to monitor natural behavior on large specimens of Atlantic cod for periods of at least four months.publishedVersio

Archived DNA reveals fisheries and climate induced collapse of a major fishery

Fishing and climate change impact the demography of marine fishes, but it is generally ignored that many species are made up of genetically distinct locally adapted populations that may show idiosyncratic responses to environmental and anthropogenic pressures. Here, we track 80 years of Atlantic cod (Gadus morhua) population dynamics in West Greenland using DNA from archived otoliths in combination with fish population and niche based modeling. We document how the interacting effects of climate change and high fishing pressure lead to dramatic spatiotemporal changes in the proportions and abundance of different genetic populations, and eventually drove the cod fishery to a collapse in the early 1970s. Our results highlight the relevance of fisheries management at the level of genetic populations under future scenarios of climate change

SNP_info

This tab-separated file contains a complete list of the SNPs analyzed in the study. For each SNP we provide the linkage group and specific linkage map position (where available), the accession reference ID (dbSNP), the original publication for the SNP discovery (source), and any miscellaneous notes

Input files

This excel file contains five sheets: SNP information, individual genotypes (baseline populations), individual genotypes (to be assigned), an input file for a multinomial likelihood ratio test and an input file binomial GLM

EnvironmentalData_Greenland

This tab-delimeted file contains the environmental data used in the BayEnv analysis of environment-allele frequency correlations. See the readme file for details