Aspects of Reproductive Biology of the European Hake (Merluccius merluccius) in the Northern and Central Adriatic Sea (GSA 17-Central Mediterranean Sea)

Michela Candelma,Daniela Bertotto,Giorgia Gioacchini,Luca Marisaldi,Sabrina Colella,Oliana Carnevali,Alberto Santojanni,Giuseppe Radaelli

doi:10.3390/jmse9040389

Abstract

The study focused on the macroscopic, histological, and biometric analysis of European hake females in GSA 17 (Central-North Adriatic Sea). From 2013 to 2015, 976 females were collected and analyzed monthly. Though females in spawning conditions were found during the whole year, the trend of GSI showed a peak of the reproductive season from April to July in 2014 and 2015. HSI and Kn reached the highest values in September, after the spawning peaks. In 2013, the trend of these indices did not highlight an evident peak, probably due to an adverse event that occurred in the previous winter in the Adriatic shelf. The length at first maturity (L50) was estimated by macroscopic and histological approaches, resulting in 30.81 cm for the macroscopical length and 33.73 cm for the histological length; both values are higher than the current catching legal size. For the first time in this area, batch and relative fecundity were estimated. Relative fecundity was similar to the Mediterranean and the Atlantic stocks, whereas batch fecundity values were lower compared to other fishing grounds. Overall, the analysis of reproductive parameters plays a fundamental role in the sustainable management of this resource in an area as overfished as the Central-North Adriatic Sea.

Highlights

In the last several decades, the excessive fishing effort, together with the increase of pollution, poor fishing management, and impairment of marine ecosystems, caused the depletion of fish stocks worldwide
In 2013, the highest value was recorded in April with a significant difference only compared to October (Tukey’s multiple comparison test; p < 0.05) (Figure 2a)
The present study is the first attempt to highlight an exhaustive knowledge of the reproductive biology of Merluccius merluccius in the Northern and Central Adriatic Sea (GSA 17) to complete the scenario of knowledge in the Italian seas

Summary

Introduction

In the last several decades, the excessive fishing effort, together with the increase of pollution, poor fishing management, and impairment of marine ecosystems, caused the depletion of fish stocks worldwide. 57.4% of fish stocks are fully exploited, 29.9% are overexploited, and only 12.7% are not fully exploited [1]. In the Mediterranean Sea, the long-lasting, intense fishing pressure applied on fish and invertebrate stocks has led to declining population biomasses [2], which has been reflected in a reduction of catches for the majority of stocks [3]. Mullon et al [4], by analyzing the FAO dataset of world fisheries catches for the period 1950–2000, detected that the major collapse occurred for demersal species. Assessed the impacts of the fishing pressure in the period 2002–2014 in the Mediterranean. Sea and determined that the Central-North Adriatic represents the highest catching area of demersal species in the Mediterranean area. The European hake (Merluccius merluccius, L. 1758) received attention because it represents one of the principal fishing targets in the Northeast Atlantic

Methods

Results

Conclusion