Spatial, interannual, and generational sources of trait variability in a marine population

Lorenzo Ciannelli; Irina Tolkova; Robert Lauth; Patricia Puerta; Thomas Helser; Alix Gitelman; Grant Thompson

doi:10.1002/ecy.2907

Spatial, interannual, and generational sources of trait variability in a marine population

Ecology. 2020 Jan;101(1):e02907. doi: 10.1002/ecy.2907. Epub 2019 Oct 29.

Authors

Lorenzo Ciannelli¹, Irina Tolkova², Robert Lauth³, Patricia Puerta^{1

4}, Thomas Helser³, Alix Gitelman⁵, Grant Thompson³

Affiliations

¹ College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, 104 CEOAS Administration Building, Corvallis, Oregon, 97330, USA.
² School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, Massachusetts, 02138, USA.
³ Alaska Fisheries Science Center, National Oceanic and Atmospheric Administration, 7200 Sand Point Way NE, Seattle, Washington, 98115, USA.
⁴ Centro Oceanografico de Baleares, Instituto Español de Oceanografía, Muelle de Poniente, s/n, 07015, Palma, Spain.
⁵ Department of Statistics, Oregon State University, 239 Weniger Hall, Corvallis, Oregon, 97331-4606, USA.

PMID: 31587266
DOI: 10.1002/ecy.2907

Abstract

Life-history traits of individuals in marine populations exhibit large sources of variability. In marine fish, variation of individual size at a given age has three main components: (1) spatial, correlated with the location in which individuals are caught, (2) temporal, correlated with the time when individuals are caught, and (3) generational, correlated with the year of birth of the examined individuals. These variations, if present, have practical implications for individual fitness as well as for sampling, survey design, and population assessment. Disentangling these variations and understanding their sources is hard, given the potentially correlated nature of their effects on individual traits. This study examines the size-at-age relationship of the Bering Sea Pacific cod, an economically and ecologically important groundfish. We used extensive records spanning 1994 to 2016 (inclusive) of 25,213 observations of both environmental variables and catch, lengths, and ages. We found that the average size of individuals of the same age could differ up to 7 cm. Notably, we found that the cohort composition of the sampled population explained >75% of the year effect and that individuals caught in the northwest and shallower portion of the sampling area were on average 5 cm smaller than individuals caught in the southern and deeper portion. We further found that northwest movement of young cod (age 1-5) as a result of warming places individuals in areas where we predict them to have smaller size at age. Smaller and less conditioned individuals are less fecund and may not be able to perform long migrations to return to their distant spawning grounds. Both the spatial distribution and water temperature experienced by Pacific cod in the Bering Sea are changing, and this study provides a mechanism for how these changes affect Pacific cod life-history traits and individual fitness.

Keywords: Bering Sea; cohort; growth; phenotypic plasticity; size at age; spatial ecology; traits.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Animals
Fishes*
Temperature