Life-history traits of the spiny dogfish Squalus acanthias in the Adriatic Sea

Giada Bargione,Mario La Mesa,Fortunata Donato,Massimo Virgili,Emilio Riginella,Carlotta Mazzoldi,Alessandro Lucchetti,Claudio Vasapollo

doi:10.1038/s41598-019-50883-w

Giada Bargione, Mario La Mesa + Show 6 more

Open Access

https://doi.org/10.1038/s41598-019-50883-w

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Abstract

Pivotal life history traits concerning age structure and reproduction of the spiny dogfish (Squalus acanthias, Linnaeus 1758) were investigated in the Adriatic Sea from mid February 2012 to mid July 2013 and in 2016. The whole sample consisted of 176 females and 150 males, ranging between 217–1025 mm and 219–875 mm, respectively. The individual age, which was estimated using a cross-sectioning technique of the second dorsal-fin spine, ranged from 0 to 13+ years for females and from 0 to 9+ years for males. Based on the length-at-age estimates, the Gompertz growth parameters were L∞ = 1130 mm, k = 0.18 and L∞ = 920 mm, k = 0.24 for females and males, respectively. The size at sexual maturity (L50) was 659 mm for females and 575 mm for males, corresponding to 7.5 and 5.5 years of age (A50), respectively. Mean biennial fecundity was approximately 11 embryos/female and 12 ripe oocytes/female. Mature males occurred during much of the sampling period, while mature females with nearly full-term embryos were exclusively recorded in May 2013 and July 2016. Monitoring of catches conducted in a sample port of the north Adriatic (Chioggia) over the past 20 years has shown fluctuating trends in landings, with peaks during the summer reproductive season.

Highlights

The Mediterranean Sea offers a unique perspective on fish population declines over historical timescales, as the resources have been highly exploited since a long time[1,2,3]
The main aim of this study is to investigate some key life-history traits of the spiny dogfish in the northern-central Adriatic Sea, an area where this species is frequently caught as bycatch
The present study reports key information on the life history traits of spiny dogfish in the northern-central Adriatic Sea, focusing the attention on age determination and reproductive biology

Summary

Introduction

The Mediterranean Sea offers a unique perspective on fish population declines over historical timescales, as the resources have been highly exploited since a long time[1,2,3]. Elasmobranchs are highly vulnerable to overfishing due to their life history characteristics that include long life span, late sexual maturity, large size at birth and low reproductive rates[4]. The main aim of this study is to investigate some key life-history traits of the spiny dogfish in the northern-central Adriatic Sea, an area where this species is frequently caught as bycatch. Basic biological characteristics such as age, growth, length-mass relationship, size frequency distributions, size and age at sexual maturity and fecundity were investigated to improve current knowledge of this species in this area. Based on official landings of the spiny dogfish of the major fishing harbor of the Northern Adriatic Sea (Chioggia), we provided information on temporal trend of catches in the last two decades to infer the status of the Adriatic spiny dogfish population

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