Reproductive biology of the holothurian Parastichopus regalis in the Mediterranean Sea and its implications for fisheries management

M Ramón,M.J Amor,E Galimany

doi:10.1016/j.fishres.2021.106191

Abstract

The sea cucumber Parastichopus regalis is a fished resource in the northwestern Mediterranean Sea but there are no studies about its reproductive biology. The aim of the present study is to characterize the reproductive ecology of P. regalis including its sex ratio, a description of the gonad and the reproductive cycle to help the implementation of a sustainable exploitation plan. A total of 1728 specimens were dissected over two years (April 2012–March 2014). The sex ratio of P. regalis was 1♀:1.2♂. The occurrence of gonads showed seasonal patterns, progressively decreasing from April to August/September and increasing from November, with a peak in March. P. regalis had an annual reproductive cycle in the northwestern Mediterranean Sea, with gonad maturation during spring and spawning in summer. No gonads were found in autumn, thus the gonadal cycle started in winter. Gonadal tubules had a larger diameter in spring in females, but seasonal differences were not found in the tubule diameter for males. The maximum percentage of P. regalis specimens with gonad per 1 cm size class did not exceed 24%. These results characterize the reproduction of P. regalis filling a key information gap for future management of the commercial fishery, which is currently not regulated. As a fishery management strategy, we propose one closed season from April to June to protect the reproductive period. The influence of evisceration in the calculations of basic fishery parameters based on the presence or weight of the gonad (size at first maturity, gonadal index) further emphasizes the importance of this study.

Highlights

Holothuroids are echinoderms found throughout the marine envi ronment, from intertidal areas and shallow seas to abyssal depths
The sea cucumber Parastichopus regalis is a fished resource in the northwestern Mediterranean Sea but there are no studies about its reproductive biology
Another environmental factor that can influence the reproductive cycle in holothurians is pluvial precipitation, which explained 29% of the total variance of the gonadal index in the shallow species Holothuria fuscoci nerea, in Mexico (Benitez Villalobos et al, 2013)

Summary

Introduction

Holothuroids are echinoderms found throughout the marine envi ronment, from intertidal areas and shallow seas to abyssal depths. They are a conspicuous and diverse group in the world’s oceans, and provide important ecosystem services as their bioturbation and deposit feeding activities enhance nutrient cycling and local productivity in sediments (Purcell et al, 2016). Sea cucumbers may be sold live, fresh, frozen, and as “trepang” (gutted, boiled, and dried). Their edible part is usually the thick body tegument other tissues may be consumed (Purcell et al, 2012). Growing interest in stock restoration has led to significant advances in culture techniques for the more valuable sea cucumber species (Lovatelli, 2004)

Objectives

Methods

Results

Conclusion