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Anchovy Early Life History and Its Relation to Its Surrounding Environment in the Western Mediterranean Basin

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Anchovy Early Life History and Its Relation to Its Surrounding Environment in the Western Mediterranean Basin View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Digital.CSIC SCI. MAR., 60 (Supl. 2): 155-166 SCIENTIA MARINA 1996 THE EUROPEAN ANCHOVY AND ITS ENVIRONMENT, I. PALOMERA and P. RUBIÉS (eds.) Anchovy early life history and its relation to its surrounding environment in the Western Mediterranean basin ALBERTO GARCÍA1 and ISABEL PALOMERA2 1Centro Oceanográfico de Málaga, Instituto Español de Oceanografía, Aptdo. 285. Fuengirola, 29640 Málaga, Spain. 2Institut de Ciències del Mar. CSIC, Passeig Joan de Borbó, s/n, 08039 Barcelona, Spain. SUMMARY: This paper is a review on the anchovy early life history in the western Mediterranean. There is evidence of latitudinal differences in the duration of the spawning period associated with regional temperature variations. The main spawning areas of the anchovy are located in the Gulf of Lyons and at the shelf surrounding the Ebro river delta. The exten- sions of spawning grounds seem to be linked to the size of the shelf and to the degree of hydrographic enriching-process- es. Punctual studies on egg and larval ecology have been made mainly in the areas of the main spawning grounds, report- ing preliminary results on growth, feeding, condition and mortality estimates. Biomass estimation by the Daily Egg Pro- duction Method (DEPM) has also been applied at the northern region. Key words: Anchovy, Engraulis encrasicolus, eggs and larvae, reproduction, Western Mediterranean. RESUMEN: PRIMEROS ESTADIOS DE DESARROLLO DE LA ANCHOA Y SU RELACIÓN CON EL AMBIENTE EN EL MEDITERRÁNEO OCCI- DENTAL. – Este trabajo es una revisión de los estudios realizados sobre las primeras fases de desarrollo de la anchoa del Mediterráneo occidental. Existen diferencias latitudinales en la duración del periodo de puesta relacionadas con las varia- ciones regionales de temperatura. Las principales áreas de puesta se encuentran en el Golfo de León y sobre la plataforma asociada a la desembocadura del río Ebro. La extensión de las áreas de puesta depende de la anchura de la plataforma y de los procesos hidrográficos de enriquecimiento. Se han realizado estudios puntuales sobre aspectos de la ecología de huevos y larvas de anchoa, principalmente en las áreas de máxima puesta, que aportan resultados preliminares básicos sobre creci- miento, alimentación, condición y estimas de mortalidad. En la región norte se ha evaluado la biomasa del estock en pues- ta en el periodo 1990-94 por medio del DEPM. Palabras clave: Anchoa, Engraulis encrasicolus, huevos y larvas, reproducción, Mediterráneo occidental. INTRODUCTION heavier on anchovy because of the higher prices brought by this species. The most abundant clupeoids off the coasts of W With regards to anchovy, its distribution along Mediterranean are sardine, Sardina pilchardus, and the European coasts off the western Mediterranean anchovy, Engraulis encrasicolus, which are the base shows greater concentrations in certain areas, fol- for the small-pelagic fishery in the region. Although lowed by discontinuities which can define differ- sardine makes up the larger share, fishing pressure is ent population units. In a W-E direction, starting at the Strait of Gibraltar, the following areas of anchovy concentration can be defined: 1) Alboran *Received December 15, 1995. Accepted June 15, 1996. Sea, 2) Spanish Levantine region, 3) Catalan Sea, ANCHOVY EARLY LIFE HISTORY IN THE WESTERN MEDITERRANEAN 155 FIG. 1. – Main areas of anchovy concentration and fishing of anchovy in the European coasts of the Western Mediterranean. 4) Gulf of Lions, 5) Ligurian and Tyrrhenian Seas son from north to south along the Catalan coast. In (Fig. 1). this area the peak spawning is always centered on The relative economic importance of this two months (Palomera, op. cit.). In the northern part resource and the need for its assesment has greate- of the region, anchovy seems to spawn at the time of ly influenced the degree of research carried out year when water temperature is high and the outflow within each region. There are very exceptional fish from the Rhône River is still substantial, creating, in egg and larval surveys extending along several of terms of stability and productivity, an environment the aforementioned regions such as the “Thor” and favourable to spawning. In the Gulf of Lions and “Dana” historical expeditions (Fage, 1920). These Catalan Sea, the most favourable environmental surveys already highlighted the importance of the conditions for spawning are encountered from June Catalano-Balearic System within the Western to August with sea surface temperatures between Mediterranean basin. 15°C and 22 °C (Fig. 2). In the Alborán Sea, the spawning period has been reported from March-April to September-October SEASONALITY with the peak in June-July (Giráldez and Abad, There have been a number of earlier studies of the spawning season of anchovy in the Western Mediterranean (D’Ancona, 1931; Fage, 1937; Demir, 1965). It appears that the species basically spawns from April to September off the coast of Spain (Andréu and Rodríguez Roda, 1951; Planas and Vives, 1951; Palomera and Rubiés, 1979; Palomera, 1992). In the eastern part of the Gulf of Lions, Chavance (1980) found anchovy eggs from May to September. There is evidence of latitudinal differences in the duration of the spawning period of the western Mediterranean associated with regional temperature fluctuations. The spawning period is more constricted at northern latitudes (five months) than at the southern ones (seven months). The mean FIG. 2. – Cumulative frequencies of anchovy eggs by temperature found during the spawning periods of 1983, 1984 and 1985 off the abundance of anchovy eggs (Palomera, 1992) Catalan Sea, by northern (close to Gulf of Lions) and southern showed the increasing duration of the spawning sea- (river Ebro delta) areas. 156 A. GARCÍA and I. PALOMERA 1995). Anchovy eggs may be found from May to beach seines and specific seines for the exploitation November (Rodríguez and Rubín, 1986; Rodriguez, of this resource (Bellón, 1950; García et al., 1981 1990), though the peak spawning usually occurs and Reina-Hervás and Serrano, 1987). This fishery during the month of August with surface tempera- motivated research in the early life history aspects of tures between 19°C and 23°C. In the Ligurian- this species, mainly focused on its distribution along North Tyrrhenian regions, Albertelli et al. (1988) the coasts (García and Rubín, 1985) and seasonality have observed anchovy spawning seasonality (Rodríguez and Rubín, 1986; Rodríguez, 1990 ). extending from May to September, with peaks in Most of the fishing effort applied to the 0-age class July. was localized in the Bay of Málaga. García et al. From the point of view of interaction with other (1981) defined this zone as an anchovy-sardine nurs- clupeiform species its interesting to note that at ery ground. Although this zone did not register the northern region anchovy and sardine do not have highest egg concentrations the existence of nursery coincident spawning period, whereas the sardine grounds was attributed to local wind induced larval spawns from October to March (Larrañeta, 1960), transport from adjacent spawning grounds. The con- the anchovy spawns from April to October, as said centration of water masses in the Bay described by before. Among other small pelagic fish present in Arévalo and García (1983) could be the cause of reten- the area, the gilt sardine (Sardinella aurita) has a tion in this area favourable to growth and feeding. spawning period in summer thus coinciding with In the northwestern sector of the Alborán Sea, anchovy peak spawning; nevertheless Palomera and near Gibraltar, divergence areas exist between the Sabatés (1990) found different distributional pat- Atlantic water inflow and the northern coasts. The terns of egg and larvae of both species indicating upwelling of deep waters in the coast near Gibraltar some degree of spatial segregation. provokes the enrichment of the surface layers. High phytoplankton productivity is associated with this region (Cortés et al., 1985), and in its immediate SPATIAL PATTERNS western borders with higher zooplankton biomass (García and Camiñas, 1985; Camiñas, 1983). Data Alboran Sea from egg and larval surveys during 1975, 1982 and 1984 have shown that the upwelling margins In the Spanish coast of the Alboran Sea the tradi- nearshore are favourable to sardine and anchovy tional coastal anchovy fishery has been targeting the spawning. However, this coastal area is under the 0-age class fraction. Its neritic distribution inshore direct influence of the Atlantic jet current which led to the development of artisanal gears, such as, after hitting the coastline on east-north-east direc- FIG. 3. – Anchovy egg distributions in the Alboran Sea during July 1993 (from Rubín, 1996). ANCHOVY EARLY LIFE HISTORY IN THE WESTERN MEDITERRANEAN 157 0 1 2 3 4 5 6 N E Anchovy eggs July 1993 43 200 m 1000 m Gulf of Lions 42 2 Eggs/0.05 m 2 41 5 Catalan Sea 10 15 25 40 1000 m 39 200 m FIG. 4. – Anchovy egg distribution in the northwestern Mediterranean Sea during July 1993. tion, may carry eggs and larvae seaward. Recent Spanish Levantine region research by Rubín (1996) showed that the Atlantic inflow can be a mechanism of egg and larval trans- Information on the distribution of anchovy port from the inmediate Atlantic spawning ground spawning grounds in this region is practically nil. located at the Gulf of Cadiz to the Mediterranean. The traditionally low catch quantities of anchovy in Little information on anchovy spawning off the this region (Abad and Giráldez, 1990) contributed to northern African coasts is available. Results from the scarcity of information from this sector. Howev- Suau and Lamboeuf (1975) and Rubín (1996) reveal er, Suau (1974) found the highest anchovy egg and rather important spawning areas off the Alhucemas larval abundances off the Gulf of Alicante in a fish Bay and near the Chafarinas island, adjacent to the egg and larval survey that covered the western Moroccan coastal waters (Fig.
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