BRAZILIAN JOURNAL OF OCEANOGRAPHY, 60(3):343-252, 2012 POPULATION BIOLOGY AND DIET OF THE SOUTHERN KINGCROAKER Menticirrhus americanus (LINNAEUS, 1758) (PERCIFORMES: SCIAENIDAE) IN CARAGUATATUBA BAY, SOUTHEASTERN BRAZIL Alexander Turra 1, Flávia Borges Santos 2, Eduardo Bessa 3, Wellington Silva Fernandez 1, *, Ligia Coletti Bernadochi 4 and Márcia Regina Denadai 4 1Instituto Oceanográfico da Universidade de São Paulo (Praça do Oceanográfico, 191, 05508-120 São Paulo, SP, Brasil) 2Universidade Estadual do Sudoeste da Bahia - Departamento de Ciências Naturais (Estrada do Bem Querer, Km 04, 45083-900 Vitória da Conquista, BA, Brasil) 3Instituto de Ciência Naturais e da Terra da Universidade do Estado de Mato Grosso (Rodovia MT-358, Km 7, 78300-000 Tangara da Serra, MT, Brasil) 4Centro Universitário Módulo (Av. Frei Pacífico Wagner, 653, 11660-903 Caraguatatuba, SP, Brasil) *Corresponding author: [email protected] A B S T R A C T This study evaluated the spatio-temporal distribution, population biology and diet of Menticirrhus americanus in Caraguatatuba Bay. Samples were taken monthly between August 2003 and October 2004, by trawling in two previously selected areas. The northern area is more exposed to wave activity and is influenced by a river, functioning as a small estuary. In contrast, the southern area is relatively sheltered from wave energy and influenced to a lesser degree by smaller rivers. The fishes' length was measured, and the sex and gonadal stage macroscopically identified. The abundance of this species was compared between areas and among months. The diet was identified and quantified. M. americanus occurred in equal proportions in the two study areas, being most abundant in April 2004, followed by December 2003 and January 2004. The population was dominated by small immature individuals. The few individuals in maturation or mature that were captured showed no seasonal pattern of distribution. This species had a varied diet, feeding on worms (nemerteans, sipunculans and echiurans), mollusks (bivalves and cephalopods), polychaetes, crustaceans and fish. The presence of intact nematodes in the intestine suggests that these are parasites. The results demonstrated that M. americanus has a homogeneous spatial and temporal distribution in Caraguatatuba Bay, being uniformly distributed between the south and north areas as well as across the months. This species can be considered a carnivorous predator, showing a preference for consuming benthic sandy-beach species such as glycerids and other polychaetes, crustaceans, and bivalve siphons. R E S U M O Este estudo teve como objetivo avaliar a distribuição espaço-temporal, biologia populacional e dieta de Menticirrhus americanus da baía de Caraguatatuba. Foram realizadas coletas mensais entre agosto de 2003 a outubro de 2004, utilizando redes de arrasto em duas áreas previamente selecionadas. A área norte é mais expostas à atividade de onda e é influenciada por um rio, constituindo um pequeno estuário. Por outro lado, a área sul é relativamente protegida da energia das ondas e sofre pouca influência dos rios. Os indivíduos coletados foram medidos e identificados macroscopicamente quanto ao sexo e o estádio gonadal. A abundância da espécie foi comparada entre as áreas e entre os meses de coleta. Para a dieta os itens alimentares encontrados foram identificados e quantificados. M. americanus apresentou proporções equivalentes nas duas áreas de estudo, sendo mais abundante em abril de 2004, seguido por dezembro de 2003 e janeiro de 2004. A população região é composta por indivíduos imaturos, e os poucos indivíduos maduros ou em maturação capturados não apresentaram padrão de distribuição ao longo do ano. A espécie mostrou uma dieta variada, alimentando-se de vermes (nemertideos, sipúnculos e equiúros), moluscos (bivalves e cefalópodes), poliquetas, crustáceos e peixes. A presença de nematóides intactos na porção do intestino sugere uma relação parasitária. Os resultados demonstraram que os indivíduos de Menticirrhus americanus estiveram uniformemente distribuídos nas áreas norte e sul e também ao longo do ano. A espécie pode ser considerada predadora e carnívora, mostrando preferência na alimentação por espécies bentônicas de fundos não consolidados, tais como geicerídeos e outros poliquetas, crustáceos e sifões de bivalves. Descriptors: Feeding, Reproduction, Spatio-temporal distribution, Betara, São Paulo. Descritores: Alimentação, Reprodução, Distribuição espaço-temporal, Betara, São Paulo. 344 BRAZILIAN JOURNAL OF OCEANOGRAPHY, 60(3), 2012 INTRODUCTION anthropic changes, such as the installation of gas pipelines, the construction of a gas treatment facility and the expansion of São Sebastião Port. The sciaenid genus Menticirrhus comprises Complementarily, State Decree no. 49,215 (December nine species that inhabit the tropical and temperate 7, 2004), which relates to the Exclusive Economic waters of the eastern Pacific and western Atlantic Zone (ZEE) of São Paulo’s northern coast, forbids (BRAUN; FONTOURA, 2004). Two species are trawling in bay areas. The present study concerns the found in Brazilian waters: M. americanus (Linnaeus, spatio-temporal distribution, size distribution, 1758) and M. littoralis (Holbrook, 1847) (MENEZES; reproductive aspects, and diet of M. americanus , one FIGUEIREDO, 1980; CARVALHO-FILHO, 1999; of the most important components of Caraguatatuba FISCHER et al ., 2004). Bay’s ichthyofauna. The observations may provide The southern kingcroaker Menticirrhus helpful information for future research and americanus , popularly known in Brazil as “Betara”, management plans for Caraguatatuba Bay, because “Papa-terra” or “Perna-de-Moça”, is distributed over this study was undertaken prior to the impacts felt in the western Atlantic from 41°N to 51°S (CHAO, this area. 1978), from Cape Cod (USA) to Argentina (CASATTI; MENEZES, 2003). It may reach 50 cm in length (MENEZES; FIGUEIREDO, 1980; MATERIAL AND METHODS CERVIGÓN, 1993) and 1,070 g in weight (IGFA, 2001). It occurs in coastal waters down to depths of 85 Study Area m (MENEZES; FIGUEIREDO, 1980; CARVALHO- FILHO, 1999), generally on sandy and muddy Caraguatatuba Bay (23 o37’S to 23 o44’S and bottoms, but also on hard-sand bottoms. Although this 45 o24’W to 45 o26’W) has a total extent of about 16 species is observed in hypersaline lagoons, young km (Fig. 1). From among the sandy beaches on the individuals often occur in low-salinity waters (CHAO, bay, two areas each of 2 x 2 km, homogeneous but 1978); the inner demersal zone, such as estuaries, is distinct from each other, were selected for this study used by this species for reproduction and growth. (Fig. 1). The locations of these areas were selected in According, M. americanus belongs to the marine- order to avoid any great influence of the local rivers estuarine ecological, the demersal vertical, the benthic- (Juqueriquerê, Lagoa and Santo Antônio) on them. fish feeding, and the summer-reproduction guilds. The first, the South area , extends from Porto Novo to The biology of M. americanus on the Palmeiras beaches and has a gentler slope; it is more southeastern and southern Brazilian coast has been exposed to wave activity and is influenced by the studied by several investigators. Ecological Juqueriquerê River, functioning as a small estuary. aspects have been analyzed by Gianini; Paiva-Filho The North area, extending from Indaiá to Centro (1992) in São Paulo and by Haluch et al. (2011) on the beaches, has a steeper slope; it is relatively sheltered Santa Catarina coast. The diet has been evaluated by from wave energy and is relatively little influenced by Juca-Chagas (1997) and Rondinelli et al . (2007) on the the smaller rivers (Lagoa and Santo Antônio). São Paulo coast, by Lunardon et al . (1991) in Paraná, and by Haluch et al . (2009) in Santa Catarina. Its Sampling Methods reproductive conditions have been assessed by Matsuura; Nakatani (1979) in São Paulo, and Muniz; Monthly samples were taken between Chaves (2008) and Haluch et al. (2011) in Santa August 2003 and October 2004. Three sampling Catarina. The condition factor has been measured by stations were randomly selected in each area, South Lunardon-Branco; Branco (1993) on the Paraná coast. and North, from among 200 possible sites; i.e. , from Other studies have examined its reproduction the total 2000-m length of the beach divided into 10-m (SMITH; WERNER, 1985; HARDING; intervals. The positions of the stations were stored in CHITTENDEN, 1987), movements and population the GPS at MLW (mean low water). dynamics (HARDING; CHITTENDEN, 1987) in the At each station, a trawl 800 m long was North Atlantic. undertaken, perpendicular to the beach and beginning However, knowledge of M. americanus as at a point 800 m from it, from a fishing boat (class well as of other members of theichthyofauna in G2M, 11 m long with a 22-HP engine). This interval is Caraguatatuba Bay, is still lacking. A pioneer project equivalent to a depth of from 1 to 4 m. The trawl in this area has been studying the mega-epifauna speed was 1 knot. The trawls were performed using populations as part of an effort to understand this two otter trawls with a mesh size of 2.0 cm, mouth ecosystem. Caraguatatuba Bay is nowhere more than 5 aperture 1.6 m high and 6.0 m wide, and bag depth of m deep, and the fishes in this environment have been 3.5 m. but little studied. The region has been undergoing TURRA ET AL.: DIET OF SOUTHERN KINGCROAKER IN CARAGUATATUBA BAY 345 Fig. 1. Caraguatatuba Bay. The study areas (South and North) are represented by the gray squares. The fish were removed from the net and were preserved in 70% ethanol until the analysis of immediately preserved in a 10% formalin solution in their contents. order to halt enzyme action and preserve the gut The guts were divided into two portions; the contents (UIEDA; CASTRO, 1999). The samples first consisted of the pharynx, esophagus and stomach, were identified and stored in plastic receptacles. In the and the second of the intestine and rectum, due to the laboratory, the specimens were identified to species different degrees of digestion of the contents in each level and transferred to 70% ethanol.