Abstract
Otolith shape analysis of Atlantic herring (Clupea harengus) in Norwegian waters shows significant differentiation among fjords and a latitudinal gradient along the coast where neighbouring populations are more similar to each other than to those sampled at larger distances. The otolith shape was obtained using quantitative shape analysis, the outlines were transformed with Wavelet and analysed with multivariate methods. The observed morphological differences are likely to reflect environmental differences but indicate low dispersal among the local herring populations. Otolith shape variation suggests also limited exchange between the local populations and their oceanic counterparts, which could be due to differences in spawning behaviour. Herring from the most northerly location (69°N) in Balsfjord, which is genetically more similar to Pacific herring (Clupea pallasii), differed in otolith shape from all the other populations. Our results suggest that the semi-enclosed systems, where the local populations live and breed, are efficient barriers for dispersal. Otolith shape can thus serve as a marker to identify the origin of herring along the coast of Norway.
Highlights
Atlantic herring (Clupea harengus, Linneaus 1758), being one of the economically most important fish species, has been a subject of several studies on population structure [1,2,3,4,5,6,7,8]
The aim of this study was to investigate the structure of local herring populations along the Norwegian coastline using otolith shape, which is a known population marker for Atlantic herring [8], to describe how discrete and diverse these smaller populations are and if so whether there were any signs of dispersal among neighbouring and more distant local populations
The samples used in this study stem from both trawl hauls using Institute of Marine Research (IMR)'s research vessel, IMR's gillnet sampling as well as samples collected by recreational fishermen, all sampled within Norwegian regulations and laws
Summary
Atlantic herring (Clupea harengus, Linneaus 1758), being one of the economically most important fish species, has been a subject of several studies on population structure [1,2,3,4,5,6,7,8]. A relatively low level of genetic differentiation has been found among isolated local populations which may overlap geographically during feeding migrations [2,3,4,5,6,9,10,11,12]. Recent studies on population genomics have revealed clear differentiation among Baltic Sea herring [5] and genetic differences have been found between the geographically isolated local herring populations in Norway, the Lake Landvik herring and herring from Trondheimsfjord, Lindåspollene and Lusterfjord [1] and within Balsfjord and Trondheimsfjord [17,18]. Studies on Atlantic herring have further revealed the plasticity and high level of adaptability of the species [19] as observed in PLOS ONE | DOI:10.1371/journal.pone.0130847. Studies on Atlantic herring have further revealed the plasticity and high level of adaptability of the species [19] as observed in PLOS ONE | DOI:10.1371/journal.pone.0130847 June 23, 2015
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