Evidence of stock connectivity, hybridization, and misidentification in white anglerfish supports the need of a genetics-informed fisheries management framework.

Imanol Aguirre‐Sarabia,Naiara Rodríguez‐Ezpeleta,Iker Pereda‐Agirre,Jorge Landa,Iñaki Mendibil,Ian Holmes,Finlay Burns,Natalia Díaz‐Arce,Agurtzane Urtizberea,Iñaki Quincoces,Jann T Martinsohn,Marina Santurtún,Ilaria Coscia,Hans D Gerritsen,Antonella Zanzi

doi:10.1111/eva.13278

Abstract

Understanding population connectivity within a species as well as potential interactions with its close relatives is crucial to define management units and to derive efficient management actions. However, although genetics can reveal mismatches between biological and management units and other relevant but hidden information such as species misidentification or hybridization, the uptake of genetic methods by the fisheries management process is far from having been consolidated. Here, we have assessed the power of genetics to better understand the population connectivity of white (Lophius piscatorius) and its interaction with its sister species, the black anglerfish (Lophius budegassa). Our analyses, based on thousands of genome‐wide single nucleotide polymorphisms, show three findings that are crucial for white anglerfish management. We found (i) that white anglerfish is likely composed of a single panmictic population throughout the Northeast Atlantic, challenging the three‐stock based management, (ii) that a fraction of specimens classified as white anglerfish using morphological characteristics are genetically identified as black anglerfish (L. budegassa), and iii) that the two Lophius species naturally hybridize leading to a population of hybrids of up to 20% in certain areas. Our results set the basics for a genetics‐informed white anglerfish assessment framework that accounts for stock connectivity, revises and establishes new diagnostic characters for Lophius species identification, and evaluates the effect of hybrids in the current and future assessments of the white anglerfish. Furthermore, our study contributes to provide additional evidence of the potentially negative consequences of ignoring genetic data for assessing fisheries resources.

Highlights

There are five individuals located in between the main three clusters. This sample grouping is coherent with the different types of genetic admixture patterns observed according to the presence of two ancestral populations, best K = 2 (Figure 3b): samples included in the first and third groups in the Principal component analysis (PCA) are not admixed and belong to different ancestral populations, and samples included in the middle group in the PCA are admixed with equal contribution from both ancestral populations
We found that several of the samples provided as white anglerfish (L. piscatorius) by expert scientists involved in surveys targeting anglerfish were black anglerfish or hybrids
To the best of our knowledge, the first evidence of natural hybridization between L. piscatorius and L. budegassa, a phenomenon that can occur between closely related species sharing morphological, ecological, and reproductive compatibilities (Montanari et al, 2014)

Summary

| MATERIAL AND METHODS

RAD-loci were assembled using the module cstacks with a maximum of 6 allowed mismatches between sample loci when generating the catalogue (parameter -n). The following steps were applied to both the de novo and reference mapped catalogs including only samples with a minimum of 30,000 RAD-loci. The module populations was used to select the tags present in RAD- loci found in at least 90% of the individuals, and PLINK version 1.07 (Purcell et al, 2007) was used to select samples with a minimum of 0.85 genotyping rate, and SNPs with a minimum of 0.95 genotyping rate and a minimum allele frequency bigger than 0.05.

| RESULTS

Findings

| DISCUSSION