Small Pelagic Resources: A Historic Perspective and Current State of the Resources

We conducted a review of small pelagic fisheries of anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) in the northern Alboran Sea (western Mediterranean Sea). This overview focuses on a long historical series of landings (from the 1940s to the present), the number of fishery vessels (from the 1970s onward), the fishery effort during the last decade, and acoustic assessment. Sardine and anchovy landings since the 1940s show very strong oscillations. The highest landings correspond to periods when the Spanish fleet could fish in the southern part of the Alboran Sea: before 1959, Morocco was not yet an independent country and later in the 1980s due to fishing agreements with that country. The fleet has been decreasing, since 1973 till nowadays; in 2017 the fleet only represents 24% of that of the year 1973. Currently, landings are low and correspond only to fishing in the northern waters of the Alboran Sea.Postprin

The small pelagic fisheries in the South-Mediterranean Region (Western Mediterranean Sea): Past and present state

A review on small pelagic fisheries of anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) in the Northern Alboran Sea (Western Mediterranean Sea) was carried out. The study was focused on a very extense historical serie of landings (from 40’s to the present), as well as the number of fishery vessels and fishery effort during the last decade, and the assessment in 200

Criteria for age estimation of anchovy otoliths in the Alborán Sea (Western Mediterranean Sea) based on the monitoring of the hyaline edge formation

Abstract This study determines the seasonality in the formation of rings in the anchovy otoliths by monitoring hyaline edge in the Alborán Sea. Monthly samples were collected between October 1989 and December 1992 from the catches of the purse seine fleet. Two hyaline zones in the otolith are deposited per year, one in winter (primary) and a minor one during the summer spawning season. The formation of hyaline rings is significantly correlated with the temperature of seawater. The highest percentage of hyaline edge formation, recorded over the four year study, periodically occurred in February, when the temperature is at its lowest. When the nutritional status of fish is better, the percentage of individuals forming hyaline edge is lower. Considering these facts, a number of criteria for interpreting the growth rings on the anchovy otolith were developed. The population is subjected to a high rate of exploitation, so with the absence of older individuals in the area, it means that growth can only be accurately described in the first year. With some variations, depending on the year, anchovy grows between 12 and 13cm in their first year of life

Long term oscillations of Mediterranean sardine and anchovy explained by the combined effect of multiple regional and global climatic indices

This study is a contribution to the PELWEB project (“Winners, losers and shifts of PELagic food WEB changes in the western Mediterranean Sea: from ecosystem consequences to future projections”, CTM2017-88939-R,2018–2020), and to “Fostering the capacity of marine ecosystem models to PROject the cumulative effects of global change and plausible future OCEANS” (PROOCEANS): Funding by Ministerio de Ciencia e Innovación, Proyectos de I+D+I (RETOS-PID2020-118097RB-I00).It is widely known that the abundance and distribution dynamics of populations of small pelagic clupeid fish, such as sardines and anchovies, are affected by large-scale climate variability, which may lead to changeovers to new regimes of small pelagics. However, long-distance climatic oscillations, such as El Niño/La Niña and the Pacific Decadal Oscillation, have been little explored in the Western Mediterranean Sea. We investigated the possible effects of the South Oscillation Index (i.e. the atmospheric oscillation coupled with the El Niño/La Niña) and Pacific Decadal Oscillation on fluctuations in catches of European anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) in the Western Mediterranean Sea, and their association with regional climate oscillations (i.e. the Atlantic Multidecadal Oscillation, the North Atlantic Oscillation, the Western Mediterranean Oscillation index, and the Arctic Oscillation)

Primer registro de anomalía intersexual gonadal de Trachurus mediterraneus (Steindachner, 1868) desde el Mar de Alborán.

El objetivo principal de este trabajo es dar a conocer el primer registro de una anomalía intersexual gonadal de Trachurus mediterraneus desde el mar de Alborán (Mediterráneo occidental). Este espécimen es el primer registro de intersexualidad para un jurel en el mundo.Postprin

Preliminary Analysis for Identification of Priority Species of Small Pelagic Shared Stocks in GSA01 And GSA03 (Alborán Sea)

Small pelagic resources and particularly sardine (Sardina pilchardus) and anchovy (Engraulis encrasicholus) represent an important fishery activity for the countries bordering the Alboran Sea. This paper aims at contributing to the identification of priority species of small pelagic shared stocks in GSA01 and GSA03 (northern and southern Alboran Sea GFCM regions) for carrying out joint stock assessments and promoting new management measures that would allow the sustainability of the resources and its exploitation. The WG on small pelagic shared stocks met twice during 2011 progressing in analysing the available data on the stocks and its exploitation and building a common data base. Moreover a comparative analysis on sardine landings data from 2003-2010 in GSA01 and GSA03 was carried out explaining that the exploitation pattern in sub-areas (GSAs 01 and 03) is different but the total length-frequency distribution of sardine exploited by each country appears to be similar. A tentative in applying a LCA analysis of the Moroccan and Spanish data on sardine using different biological parameters and with the VIT software was unsuccessful but orientated for future works of the W

Age determination procedures for benthic fish in Spanish Institute of Oceanography (IEO)

This handbook presents a summary of the age estimation procedures used in the Spanish Institute of Oceanography (IEO) for some of the main commercial benthic species of fish for the Spanish fleet: megrim (Lepidorhombus whiffiagonis), four spot megrim (Lepidorhombus boscii), white anglerfish (Lophius piscatorius), black anglerfish (Lophius budegassa). It provides information about the sampling program, the morphology of hard parts (otoliths and illicia), their extraction, preparation, and the age estimation criteria. A summary of information related to the accuracy, validation and corroboration of age of each species is also presented, as well as that related to the precision, quality control and verification of age

Zooplankton Biomass Depletion Event Reveals the Importance of Small Pelagic Fish Top-Down Control in the Western Mediterranean Coastal Waters

The influence of hydrochemistry and trophic conditions on the coastal zooplankton community’s biomass and metabolic activities was investigated along the Spanish Mediterranean coastal waters, from Algeciras Bay to Barcelona, from autumn 2011 to autumn 2012. Two hydrographic regions were differentiated: NW Alboran (ALB) and W Mediterranean (MED). Zooplankton metabolism was assessed from measurements of the electron transport system (ETS) and aminoacyl-tRNA synthetases (AARS) activities, as proxies for potential respiration and somatic growth, respectively. Zooplankton showed three to fivefold higher biomass in ALB than in MED during autumn 2011 and spring 2012. However, in autumn 2012, a drastic decrease in biomass standing stock was observed in ALB, with no significant differences between the two regions. This biomass depletion event was not associated with environmental variables, food availability or zooplankton metabolic rates, but coincided with a twofold peak of Sardina pilchardus landings in ALB. A reduced standing stock coupled with high zooplankton growth rates suggests mortality by predation as the main cause for the low zooplankton biomass typically observed in MED, and in ALB during autumn 2012.Versión del edito

Influence of Dietary Lipids and Environmental Salinity on the n-3 Long-Chain Polyunsaturated Fatty Acids Biosynthesis Capacity of the Marine Teleost Solea senegalensis

Fish vary in their ability to biosynthesise long-chain polyunsaturated fatty acids (LC-PUFA) depending upon the complement and function of key enzymes commonly known as fatty acyl desaturases and elongases. It has been reported in Solea senegalensis the existence of a Δ4 desaturase, enabling the biosynthesis of docosahexaenoic acid (DHA) from eicosapentaenoic acid (EPA), which can be modulated by the diet. The present study aims to evaluate the combined effects of the partial replacement of fish oil (FO) with vegetable oils and reduced environmental salinity in the fatty acid composition of relevant body compartments (muscle, hepatocytes and enterocytes), the enzymatic activity over α-linolenic acid (ALA) to form n-3 LC-PUFA through the incubation of isolated hepatocytes and enterocytes with [1-14C] 18:3 n-3, and the regulation of the S. senegalensis fads2 and elovl5 in the liver and intestine. The presence of radiolabelled products, including 18:4n-3, 20:4n-3 and EPA, provided compelling evidence that a complete pathway enabling the biosynthesis of EPA from ALA, establishing S. senegalensis, has at least one Fads2 with ∆6 activity. Dietary composition prevailed over salinity in regulating the expression of fads2, while salinity did so over dietary composition for elovl5. FO replacement enhanced the proportion of DHA in S. senegalensis muscle and the combination with 20 ppt salinity increased the amount of n-3 LC-PUFA in hepatocytes