Relative seasonal fish abundance caught by recreational fishery on Cidreira Pier, southern Brazil

Introduction

Recreational fishing is an important source of information which is frequently neglected by the fishery scientist. The species captured, or even the impact on natural populations, is usually unknown. In the present work, a list of species captured by recreational fishermen in southern Brazil is presented, including a relative indication of seasonal fish abundance. The occurrence of the various fish species is compared with a previous study on the distribution and abundance of demersal bony fish captured by the industrial fishery on the continental shelf of southern Brazil ( Haimovici 1996) .

Materials and methods

Samples were taken monthly from May 1997 to May 1998, with more than 60 days (daylight only) of observation of recreational fishing at Cidreira Pier 30°08′57.7″S; 050°11′25.5″W. The pier is a concrete construction extending 340 m into the ocean (open sea) from the shoreline to beyond the surf zone and reaching depths from 3 to 4 m on a substrate of fine quartz sand. Captures were exclusively by hook-and-line using various hook sizes ranging from 6 to 23 mm hook width. Water temperatures range from 12.5°C in winter to 23°C in summer, depending on the dominant current. Information on biotic and abiotic characteristics of the sample area are found in Seelinger (1997). Species identification was according Ringuelet (1960), Figueiredo (1977), Figueiredo (1978 , Figueiredo (1980), Menezes (1980 , Menezes (1985), and Higuchi (1982). As the sampling programme was originally designed to analyze growth and reproduction of Menticirrhus littoralis and Paralonchurus brasiliensis, data on catch effort were not collected. The frequency classifications of fish occurrences are subjective and should be considered as rough indications of relative abundance. In the present study, a ‘dominant’ species was identified when it occurred among the two or three more frequently captured species in the specified season; ‘common’ means frequently captured but not dominant in the aforementioned sense; an ‘occasional’ occurrence was registered when the species was observed at a reduced frequency. A species was considered as ‘rare’ when only one or two observations of that species were made during the specified season. It should be noted that the influence of the El Niño phenomena, which increases temperature and rainfall in southern Brazil, may have led to atypical results of seasonal abundance.

Results and discussion

Thirty-one species from 16 families were captured; they are summarized in Table 1. In accordance with results from Haimovici et al. (1996) , fish from the family Sciaenidae were most frequently captured, representing almost one-third of the species encountered. Among these, Menticirrhus americanus, Menticirrhus littoralis and Paralonchurus brasiliensis were the dominant species, mainly captured in autumn, winter and spring. Micropogonias furnieri, because of its size and abundance, is an important fishery resource in spring.

Table 1. Relative frequency of species captured at Cidreira Pier, southern Brazil, from May 1997 to May 1998

Frequency of capture showed a seasonal pattern, therefore the species could be divided into two general groups: annual species, observed with similar frequency throughout the year; and seasonal species, captured with higher frequency in a specified season. The first group (annual) included Netuma barba, Netuma planifrons, Odontesthes argentinensis, Trachinotus marginatus, Menticirrhus americanus, Menticirrhus littoralis and Trichiurus lepturus.

The seasonal group could be divided into autumn/winter or spring/summer dominant species.

The autumn/winter species included Genidens genidens, Urophycis brasiliensis, Pomatomus saltatrix, Trachinotus goodei, Ulaema lefroii, Macrodon ancylodon and Paralonchurus brasiliensis.

The spring/summer species were Micropogonias furnieri, Pogonias cromis, Stellifer rastrifer, and mainly Chondricthyes, including Sphyrna lewini, Rhinobatus percellens, Myliobatis goodei, and Rhinoptera bonasus. When present, Rhinobatus percellens and Sphyrna lewini were captured in large quantities, suggesting schooling formations. Sphyrna lewini examples were newly born, with total lengths ranging from 40 to 50 cm.

Carcharhinus sp., Rhizopriodon sp., Zapteryx brevirostris, Ophichthus gomesii, Bregmaceros atlanticus, Caranx crysos, Eucinostomus gula, Cynoscion guatucupa, Stellifer brasiliensis and Scomber japonicus were not classified, since the small numbers of their capture do not permit any conclusions on their seasonal occurrence.

From a comparison of the present data with Haimovici et al. (1996) , it could be concluded that industrial trawl fisheries and recreational hook-and-line fisheries mainly affect different fish stocks.

Although Cynoscion guatucupa, Trichiurus lepturus, Urophycis brasiliensis and Umbrina canosai were the four most frequently captured species by bottom trawling according Haimovici (1996), they were of no importance in recreational fishing. Cynoscion guatucupa only rarely appeared in spring; Urophycis brasiliensis were occasionally captured in autumn and winter; Trichiurus lepturus were captured in all seasons but with low frequency; and no Umbrina canosai were captured throughout the year.

In contrast, Paralonchurus brasiliensis, Menticirrhus americanus and Menticirrhus littoralis, which are major captures in recreational fishery, are ranked in positions 10, 21, 36, respectively (by absolute frequency) in bottom trawl surveys ( Haimovici et al. 1996 ).

Some similarity on stock exploration occurs with Micropogonias furnieri, the fifth-ranking species in industrial absolute frequency of capture. When they migrate near the shore in spring to spawn ( Haimovici et al. 1996 ), large individuals of these species, usually more than 40 cm total length, are intensively captured by recreational fishermen. Considering the stock reduction of Micropogonias furnieri as mentioned by IBAMA (1995) and Haimovici et al. (1996) , then a springtime fishery restriction of Micropogonias furnieri should be considered.