SciELO - Scientific Electronic Library Online

 
vol.38 número2Prevalencia estacional de la enfermedad de la plaga blanca en el coral endémico de Brasil Mussismilia braziliensis índice de autoresíndice de materiabúsqueda de artículos
Home Pagelista alfabética de revistas  

Servicios Personalizados

Revista

Articulo

Indicadores

Links relacionados

Compartir


Latin american journal of aquatic research

versión On-line ISSN 0718-560X

Lat. Am. J. Aquat. Res. v.38 n.2 Valparaíso  2010

 

Lat. Am. J. Aquat. Res., 38(2): 297-301, 2010
DOI: 10.3856/vol38-issue2-fülltext-17

Short Communication

 

On the presence of Illex argentinus (Castellanos, 1960) (Cephalopoda: Ommastrephidae), paralarvae and juveniles in near-shore waters of Nuevo Gulf, Argentina

Presencia de paralarvas y juveniles de Illex argentinus (Castellanos, 1960) (Cephalopoda: Ommastrephidae) en aguas costeras del Golfo Nuevo, Argentina

 

Augusto Crespi-Abril1, Fernando Dellatorre1 & Pedro Barón1

1   Centro Nacional Patagónico (CENPAT-CONICET), Boulevard Brown s/n Puerto Madryn, Chubut, Argentina

Dirección para correspondencia


ABSTRACT. In this study we report the presence of paralarvae and juveniles oflllex argentinus in the waters of Nuevo Gulf (42°45'S-64°45'W, Argentina) during three consecutive years (2004-2007). Paralarvae were caught using a Hensen net of 295 µm mesh size. Juveniles were found stranded on the coast in September 2007. These findings show that the species uses near-shore waters for breeding.

Keywords: early life stages, Ommastrephid, near-shore waters, nursery grounds, Argentina.


RESUMEN. En este estudio reportamos la presencia de paralarvas y juveniles de Illex argentinus en aguas del Golfo Nuevo (42°45'S-64°45'W, Argentina) durante tres años consecutivos (2004-2007). Las paralarvas fueron capturadas usando una red Hensen de 295 µm de malla. Los juveniles se hallaron varados en la costa en septiembre de 2007. Estos registros son evidencia de que esta especie utiliza aguas costeras para la cría.

Palabras clave: estadios tempranos de vida, Ommastréfido, aguas costeras, areas de cría, Argentina.


The location of spawning and nursery grounds of squids from the genus Illex, as well as that of other ommastrephids, has been frequently associated to areas subjected to the influence of major oceanic currents (e.g. Gulf Stream, Kuroshio-Oyashio) because of the favorable hydrographic conditions for egg mass and paralarvae survival they genérate (e.g. high primary productivity, particle retention and transport, adequate temperatures for embryonic development) (Bakun & Csirke, 1998). The geographic area of distribution of Illex argentinus (Castellanos, 1960), the second most important cephalopod fishery in volume of captures (FAO, 2008), is also under the influence of an interactive system comprising two major currents. The southward-flowing Brazil current dominates the northern part of the región while the northward-flowing Malvinas (Falkland) current affects the southern part (Olson et al., 1988). According to several authors (Brunetti & Ivanovic, 1992; Haimovici et al., 1998; Waluda et al., 2001), their confluence, near the mouth of La Plata River, genérate oceanographic conditions that support embryonic and paralarvae development.

Based on information about the presence of mature and spent individuals, egg masses and paralarvae, it has been reported that mature I. argentinus from the outer-shelf and slope populational units (South Patagonic and Bonaerensis-North Patagonic Stoks) concéntrate and spawn on the slope, egg masses are transported northward by the Malvinas (Falkland) Current, and hatching occurs near the confluence with the Brazil Current (Haimovici et al., 1998; Arkhipkin, 2000; Laptikhovsky et al., 2001; Waluda et al., 2001, 2005). Additionally, the presence of juveniles reveáis the existence of a populational unit (Summer Spawning Stock) spawning on the mid-shelf (Brunetti & Ivanovic, 1992; Haimovici et al., 1998).

Nevertheless, it has been suggested that this unit represents only a small fraction of that of the whole population (less than 1%) (Bakun & Csirke, 1998; Carvalho & Nigmatullin, 1998). It has been demonstrated that several areas along mid and outer shelf off Argentina present physical and biological conditions such that they act as spawning and nursery grounds (e.g. tidal frontal zones) (Brunetti, 1990; Brunetti & Ivanovic, 1992; Haimovici et al., 1998; Waluda et al., 2001; Rivas et al., 2006; Romero et al., 2006). In contrast, efforts directed to determine if near-shore waters are suitable habitats for early-life stages of the species have been sparse and unsuccessful in detecting their presence (Brunetti & Ivanovic, 1992; Leta, 1992; Haimovici et al., 1998). To improve this situation, we examined the presence of paralarvae and juveniles of I. argentinus in waters of Nuevo Gulf (NG) (Fig. 1), one of the three northern Patagonian gulfs (along with San José and San Matías gulfs), by sampling zooplankton during two conse-cutive years (2005 to 2006).


Figure 1. Map of Nuevo Gulf. Left: geographic location; right: bathymetry (m).

Figura 1. Mapa de Golfo Nuevo. Izquierda: ubicación geográfica; derecha: batimetría (m).

Nuevo Gulf (Fig. 1) is a semi-enclosed basin 2.44x109 m2 in surface area and 2,54x1011 m3 in volume, with mean and maximum depths of 90 and 170 m respectively (Rivas & Ripa, 1989; Rivas, 1990). Its narrow mouth, 16 km in width and 7,13x105 m2 in transverse section, opens to the inner shelf off northern Patagonia. Estimations of mean monthly chlorophyll-a concentration at its western sector range within 0.20- 4.20 mg m-3 (Gil, 2001).

From August 2004 to April 2006, 70 plankton hauls (2-3 knots of towing speed) were performed with a 295 ixm-mesh size Hensen net (70 cm of diameter) equipped with a flowmeter (Ogawa Seiki) on board of the research vessel CENPAT I and the coastal guard vessel Lago Musters (Prefectura Naval Argentina) in waters of Nuevo Gulf. From August 2004 to July 2005, 24 tows were performed in day hours. Nine of them were horizontal and conducted at sub-surface near the west coast of Nuevo Gulf (between 6 and 10 m bottom depth), and 15 were oblique, from deeper waters (between 35 and 50 m bottom depth) to surface. In the oblique hauls, the net was held during five minutes at approximate depths of 30, 15, and 2 m. From August 2005 to April 2006, 46 stratified horizontal tows were performed in areas with 35 and 85 m bottom depth (18 during night hours and 28 during day hours). The net was towed at different depths on each haul to sample different strata in the water column (3, 10, 30, and 70 depth approximately). Additionally, stranded juveniles of I. argentinus were collected in September 2007. Both paralarvae and juveniles were identified by comparison with reference material and descriptions available on the literature (Brunetti, 1990; Wormuth et al., 1992; Vidal, 1994). For each specimen a number of body dimensions were measured (Fig. 2). All of the specimens were included in the catalog of the marine invertebrate collection of the Commercial Fish and Shellfish Laboratory of the National Patagonian Center (LAPEMAR-CENPAT) and are available for further examination.


 

Figure 2. Schematic representation of an Illex argentinus paralarvae showing body dimensions registered in this study. FW: fin with, ML: mantle length, FL: fin length, HW: head with, AL: arms length, TL: tentacle length.

Figura 2. Representación esquemática de la paralarva de Illex argentinus donde se muestran las dimensiones registradas en este studio. FW: ancho de la aleta, ML: largo del manto, FL: longitud de la aleta, HW: ancho de la cabeza, AL: longitud de los brazos, TL: longitud de los tentáculos.

Paralarvae of I. argentinus were found in one out of 22 hauls conducted in summer and one out of 17 performed in fall. No paralarvae were found in winter (20 hauls) and spring (9 hauls). A total of five paralarvae (one in March 2005 and four in April 2006) were obtained from an estimated volume of 9674 m3 of seawater filtered as part of the zooplankton monitoring program in Nuevo Gulf. The paralarvae (mean mantle length: 7.6 mm) were captured at depths lower than 30 m (Table 1). Additionally, in September of 2007, 10 stranded juveniles (mean mantle length: 36.2 mm) were collected on a beach located at the western margin of Nuevo Gulf (Table 1). Also, three paralarvae of Loligo sanpaulensis, identified following Baron (2003), were found in the samples.

Previous findings of I. argentinus paralarvae were summarized by Haimovici et al. (1998), but were all referred to mid and outer shelf and slope samplings. The scarcity of information on the relevance of near-shore waters for the reproduction and breeding of the species may have lead to the sub-estimation of the extension of the spawning and nursery grounds. In a previous study, Crespi-Abril et al. (2008) pointed out that I. argentinus uses near-shore waters of northern Patagonia (San Matías Gulf) for mating and probably for spawning. The finding of paralarvae in two consecutive years and juveniles in the following year in Nuevo Gulf evidences that breeding of I. argentinus, and probably hatching, are viable within the northern Patagonian gulfs. Although the abundance of squid paralarvae in our samples seems to be low, valúes are not far from those reported in some of the previous studies conducted on the shelf and slope (Haimovici et al., 1998). Some causes for these low captures could be the patchy distribution of these organisms, their low densities and the underestimation of their ability to elude the nets (Haimovici et al., 2002). On the other hand, the seasonality of hatching and breeding could restrict the presence of these life stages in the water column to a limited period of the year. Overall, from our observations it becomes evident that there is a need for more exhaustive and extensive sampling in near-shore waters to determine how significant is the contribution of I. argentinus offspring breed in near-shore waters compared to that of the shelf and slope.

ACKNOWLEDGEMENTS

Part of the samplings conducted in this study were founded by project BID OC-AR 1728 PICT 14700 from the Argentinean National Agency of Scientific and Technologic Promotion (ANPCYT). Our special thanks are due to the team of the Nautical Department from National Patagonian Center (CENPAT, CONICET) for is contribution to the sampling of squid juveniles; to Nerina Figueroa and Laura Rojas for their contribution in laboratory work; to Natalia Ledesma Covi for her contribution to the paper's artwork, and to Prefectura Nacional Argentina Puerto Madryn for they support during the collection of samples. Also, we thank two anonymous reviewers for their helpful comments.

 

REFERENCES

Acha, E.M., H.W. Mianzan, R.A. Guerrero, M. Favero & J. Bava. 2004. Marine fronts at the continental shelves of austral South America: physical and ecological processes. J. Mar. Syst., 44: 83-105.        [ Links ]

Arkhipkin, A. 2000. Intrapopulation structure of winter-spawned Argentine shortfin squid, Illex argentinus (Cephalopoda, Ommastrephidae), during its feeding period over the Patagonian Shelf. Fish. Bull., 98: 1-13.        [ Links ]

Bakun, A. & J. Csirke. 1998. Environmental process and recruitment variability. In: P. Rodhouse, E. Dawe & R. O'Dor (eds.). Squid recruitment dynamics. The genus Illex as a model, the commercial Illex species and influences on variability. FAO Fish. Tech. Pap., 376: 105-124.        [ Links ]

Barón, PJ. 2003. The paralarvae of two South American sympatric squid: Loligo gahi and Loligo sanpaulensis. J. Plankton Res., 23: 1347-1358.        [ Links ]

Brunetti, N. 1990. Description of rhynchoteuthion larvae of Illex argentinus from summer spawning population. J. Plankton Res., 12: 1045-1057.        [ Links ]

Brunetti, N. & M. Ivanovic. 1992. Distribution and abundace of early life stages of squid (Illex argentinus) in the south-west Atlantic. ICES J. Mar. Sci.,49: 175-183.        [ Links ]

Carvalho, G.R. & Ch.M. Nigmatullin. 1998. Stock structure analysis and species identification. In: P. Rodhouse, E. Dawe & R. O'Dor (eds.). Squid recruitment dynamics. The genus Illex as a model, the commercial Illex species and influences on variability. FAO Fish. Tech. Pap., 376: 199-232.        [ Links ]

Crespi-Abril, A.C., E.M. Morsan & PJ. Barón. 2008. Contribution to understanding the population structure and maturation of Illex argentinus (Castellanos, 1960): the case of the inner-shelf spawning groups in San Matías Gulf (Patagonia, Argentina). J. Shellfish Res., 27: 1225-1231.        [ Links ]

Food and Agriculture Organization (FAO). 2008. Fishstat plus (v. 2.30). GFCM (Mediterranean and black sea) capture production 1970-2006. Also downloadable at: http://www.fao.org/fi/statist/FISOFT/FISHPLUS.asp.        [ Links ]

Gil, M.N. 2001. Eutroficación: rol del nitrógeno en ambientes marinos costeros. PhD Thesis. Universidad Nacional del Sur, Bahía Blanca, Argentina, 132 pp.        [ Links ]

Haimovici, M., N. Brunetti, P. Rodhouse, J. Csirke & R. Leta. 1998. Illex argentinus. In: P. Rodhouse, E Dawe & R O'Dor (eds.). Squid recruitment dynamics. The genus Illex as a model, the commercial Illex species and influences on variability. FAO Fish. Tech. Pap., 376: 27-58.        [ Links ]

Haimovici, M., U. Piatkowski & R. Aguiar dos Santos. 2002. Cephalopod paralarvae around tropical seamounts and oceanic islands of the northeastern coast of Brazil. Bull. Mar. Sci., 71(1): 313-330.        [ Links ]

Laptikhovsky, V., A. Remeslo, Ch.M. Nigmatullin & LA. Polishchuk. 2001. Recruitment strength forecasting of the shortfin squid Illex argentinus (Cephalopoda: Ommastrephidae) using satellite SST data, and some consideration of the species' population structure. Copenhagen Denmark ICES, K15: 1-9.        [ Links ]

Leta, H.R. 1992. Abundance and distribution of Illex argentinus rhynchoteuthion larvae (Cephalopoda, Ommastrephidae) in the waters of the southwestern Atlantic (Argentine-Uruguayan common fishing zone). S. Afr. J. Mar. Sci., 12: 927-941.        [ Links ]

Olson, D.B., G.P. Podestá, R.H. Evans & O.B. Brown. 1988. Temporal and variation in the separation of the Brazil and Malvinas currents. Deep-Sea Res., 35: 1971-1990.        [ Links ]

Rivas, A.L. 1990. Heat balance and annual variation of mean temperature in the North-Patagonian gulfs. Oceanol. Acta, 13(3): 265-272.        [ Links ]

Rivas, A.L. & P. Ripa. 1989. Variación estacional de la estructura termo-halina de golfo Nuevo, Argentina. Geofís. Int., 28: 3-24.        [ Links ]

Rivas, A.L., A.L. Dogliotti & D.A. Gagliardini. 2006. Seasonal variability in satellite-measured surface chlorophyll in the Patagonian Shelf. Cont. Shelf Res., 26: 703-720.        [ Links ]

Romero, S.I., A.R. Piola, M. Charo & C.A. Eiras García. 2006. Chlorophyll-a variability off Patagonia based on SeaWifs data. J. Geophys. Res., 111. C05021. [doi: 10.1029/2005 JC003244]        [ Links ]

Vidal, E.A. 1994. Relative growth of paralarvae and juveniles of Illex argentinus (Castellanos, 1960) in southern Brazil. Antarct. Sci., 6: 275-282.        [ Links ]

Waluda, C.M., P.G. Rodhouse, G.P. Podestá, P.N. Trathan & GJ. Pierce. 2001. Surface oceanography of the inferred hatching grounds of Illex argentinus (Cephalopoda: Ommastrephidae) and influences on the recruitment variability. Mar. Biol., 139: 671-679.        [ Links ]

Waluda, C.M., P.N. Trathan & P.G. Rodhouse. 2005. Influence of oceanographic variability on recruitment in the Illex argentinus (Cephalopoda: Ommastrephidae) fishery in the South Atlantic. Mar. Ecol. Progr. Ser., 183: 159-167.        [ Links ]

Wormuth, J.H., R.K. O'Dor, N. Balch, M.C. Dunning, E.C. Forch, R.F. Harman & T.W. Rowell. 1992. Family Ommastrephidae Steenstrup, 1857. In: MJ. Sweeney, C.F.E. Roper, K.M. Mangold, M.R. Clarke & S.V. Boletzky (eds.). Larval and juvenile cephalopods: a manual for their identification. Smith. Contrib. Zool., 513: 105-119.        [ Links ]

 

Corresponding author: Augusto Crespi-Abril (crespi@cenpat.edu.ar)

Received: 16 June 2009; Accepted: 4 May 2010