Checklist of marine demersal fishes captured by the pair trawl fisheries in Southern ( RJ-SC ) Brazil

Demersal fishery resources are abundant on continental shelves, on the tropical and subtropical coasts, making up a significant part of the marine environment. Marine demersal fishery resources are captured by various fishing methods, often unsustainably, which has led to the depletion of their stocks. In order to inventory the marine demersal ichthyofauna on the Southern Brazilian coast, as well as their conservation status and distribution, this study analyzed the composition and frequency of occurrence of fish captured by pair trawling in 117 fishery fleet landings based in the State of São Paulo between 2005 and 2012. The ichthyofauna consisted of 245 species (81 families, 32 orders and 2 classes). Among the species, 50 species were classified as constant, 38 accessory and 157 accidental. Still, 13.47% of the species were listed as endangered; 35.29% of the Chondrichthyes and 11.85% of the Actinopterygii (15.1% of the total species) belong to the endemic fauna of the Biogeographic Province of Argentina. The richness was directly related to the oceanographic features of the study area, which determined the southern boundary of occurrence of several tropical species and the northern boundary of occurrence for temperate species. This is the region with the highest abundance of fishery resources in Brazil.


Introduction
Demersal fishery resources are abundant on continental shelves, on the tropical and subtropical coasts, making up a significant part of the marine environment.Oceanographic conditions influence the quality and potential of such resources, as well as regionally limit the use of certain types of vessels and fishing gear (Yáñez-Arancibia & Sánches-Gil 1988, Dias-Neto & Ximenes 1998).
The capture of demersal species has been carried out by artisanal and industrial fishing for several decades and it is one of the most important activities for the fishing industry in Brazil (Castro et al. 2003).Smallscale fishing consists of beach seining, gillnets, long-lines, stern trawlers or double rig trawlers along estuarine and coastal and regions.Industrial fishing is carried out by medium and large-sized vessels using pair trawls and otter trawlnets, stern trawlers or double rig trawlers, gillnets and long-lines, as well as fishing with traps, coves and purse seines (Sudepe 1985, Valentini et al. 1991, Ibama 1993, 1995, Haimovici 1997).
According to Caddy & Sharp (1986), it is necessary to bear in mind that exploited species are linked to others that may be essential for the economic and biological productivity of the ecosystem.This is the only way to minimize the adverse effects of fishing and not to compromise the system's ability to sustain productive human activity.Therefore, the proper management of exploited resources and aquaculture requires knowledge about the dynamics of communities/populations, their ecological interactions, the integration with physicochemical and biological processes at spatial and temporal scales, as well as changes in fishery dynamics (Yáñes-Arancibia et al. 1985, Davis & Anderson 1989, Aryuthaka & Thumbthimsang 1992, Castelo et al. 2007, Castro & Tutui 2007).
This study provides a checklist of marine demersal ichthyofauna of the southern coasts of Brazil captured by the fishery fleet pair trawling based in the state of São Paulo and comments upon the composition, frequency of occurrence, conservation status and geographical distribution of the recorded species.

Material and Methods
The pair trawling fleet operation area had its limits under the coordinates 23º04'S / 42º20'W near Cabo Frio -RJ and 29º19'S / 49º41'W in Torres -RS.Prior to SMA-SP Resolution No. 69 of 2009, activities were concentrated on the south coast of São Paulo under the coordinates 24º31'S / 46º39'W near Peruíbe -SP and 28º37'S / 48º37'W near Cabo de Santa Marta -SC ( Figure 1).
The following sampling routine was performed for qualitative purposes: (a) the whole screening operation of the marketable product was followed up by collecting all rejected material among commercial products and also part of this products; (b) samples of the rejected and discarded products that fishermen sampled during the whole fishing operation were collected for further evaluation in the laboratory; c) co-ordinates of the most distant bids, as well as of the main fishing grounds and their respective depths, were annotated with the masters.Samples of rejected and discarded fauna were also obtained through 15 shipments to the studied fleet.
The collected specimens were referred to the laboratory in iceboxes.Samples were identified, counted and had their total length measured (in mm).Subsequently, the specimens were fixed in 10% formaldehyde and preserved in 70% ethyl alcohol.Voucher specimens of the some species collected during the study were deposited in the regional collection of fish from the Atlantic Forest coast of the "Acervo Zoológico da Universidade Santa Cecília" (AZUSC), in the city of Santos-SP, Brazil.
Species were classified from their frequencies of occurrence and according to the Dajoz's (1983) scale as "constant" when present in more than 50% of the samples; "accessory" when frequencies ranged from 25 to 50% and "accidental" when frequencies were below 25%.
The conservation status of each species were based on the International Red List of threatened species (IUCN -International Union for Conservation of Nature 2017) and the Brazilian Federal list of threatened species, Ordinance number 445 of the MMA -Brazilian Environment Ministry, December 17th 2014 (MMA 2014).
Species were classified in the biogeographical categories proposed by Floeter et al. (2008) and Luiz Jr. et al. (2008).
When considering only the Critical, Endangered and Vulnerable categories, both by the IUCN (2017) criteria and by Brazilian federal Legislation (MMA 2014) we observed a total of 33 threatened species (13.47%) in this study.Also, when considering only the threat categories and choosing the most conservative classification, three distinct and worrying scenarios are drawn by correlating the conservation status with the frequency of occurrence (constant, accessory and accidental) (Table 4).
Table 4. Checklist of the threatened species captured according to the International Union for Conservation of Nature (IUCN 2017) and the Brazilian list (MMA 2014) and their frequency of occurrence (Dajoz 1983).

Accidental
Accessory Constant

Discussion
The richness of demersal organisms is directly related to the continental shelf width, sediment types, oceanographic conditions, the geological events that shaped the continental shelf, as well as its positioning relative to the equator characterizing the environmental temperature (Lowe-McConnell 1987, Longhurst & Pauly 2007).
Although many results of this study can be explained by the oceanographic features of the pair trawling fleet operation area in the state of São Paulo, biotic factors interfere with the species distribution through inter-and intraspecific relations, such as the predator-prey effect and the competitive interactions for food (Sanders 1969, Moyle & Cech 1998, Menge & Olson 1990, Barry et al. 1996, Akin et al. 2003).
Overall, the widest and largest continental shelf is in southern Brazil, consisting of muddy sediment and under the influence of the oscillation of the subtropical convergence between the warm waters of the Brazilian current and the cold waters of the Malvinas current.The region has upwelling zones that during the summer and spring cause the South Atlantic Central Water (SACW) to penetrate the shelf reaching the coastal areas with a thermocline of 10 and 15 meters.During the winter, SACW retracts and Tropical Water (TW) fills the space.There is significant water input from continental drainage.Due to such characteristics, the region represents the Southern boundary of occurrence of several tropical species (e.g.: Hypanus guttatus, H. americanus, Anchoa tricolor, Rypticus randalli) and the Northern boundary of temperate species (e.g.: Atlantoraja castelnaui, A. cyclophora, Sardinella brasiliensis, Boridia grossidens).Moreover, the region has the highest abundance of fishery resources in Brazil (Pires-Vanin et al. 1993, Matsuura 1995, Castro & Menezes 1998, Menezes et al. 2003, Braga & Niencheski 2006, Castro et al. 2006, Castro et al. 2008, Amaral & Nallin 2011, Menezes 2011).
According to Menezes et al. (2003), 1,297 species of marine fish, belonging to 36 orders and 192 families, occur in Brazil.The results of this study showed the Southern demersal ichthyofauna accounted for 18.9% of species recorded in Brazil.The families Carangidae, Sciaenidae, Paralichthyidae, Haemulidae, Serranidae and Engraulidae showed high number of species, with most species being demersal, benthic or benthopelagic (Lowe-McConnell 1987).
According to Dajoz's (1983) scale, we could hypothesize that the common richness of the ichthyofauna by landing is approximately 90 species (constant + accessory).However, this value differs from that observed in landings, which ranged from 49 to 104 species (mean and standard deviation = 68.65 ± 13.20), mainly due to the high number of accidental species.
According to criteria adopted by the International Union for Conservation of Nature (IUCN 2017), species classified as least concern (64.08%) were predominant, followed by not-evaluated species (14.69%), data deficient (8.16%), vulnerable and nearthreatened (4.90%), endangered (2.45%) and critically endangered (0.82%).Based on Brazilian federal legislation (MMA 2014), only 10.61% of the species are threatened regarding the conservation status: 4.49% endangered, 3.67% vulnerable and 2.45% endangered.Proportionally, Class Chondrichthyes had higher number of highly endangered species (23.53% critically endangered, 11.76% endangered and 20.59% vulnerable).Based on the three scenarios observed regarding the conservation status of the captured species, the actions of fishery management are priority for the pair trawling fishing operating in the Zoogeographic Province of Argentina.We emphasize this study was carried out in the period before the prohibitions on the capture of several endangered species (MMA 2014); therefore, the continuous monitoring of the composition of this fishing modality is necessary.We also point out there were restrictions of fishing area for pair trawling fishing in the State of São Paulo (SMA 2009).Such restrictions occurred during the last 3 years of this study, which again emphasizes the need for continuous monitoring to verify changes in the composition of the species captured by this type of fishery.
According to Kotas (1991), the pair trawling fishing is characterized as active, multispecies and difficult to manage due to the large number of species captured.The most used management technique in these cases is the restriction of areas and/or periods (High et al. 1969, Caddy 1982), which often causes economic and social problems.There are other ways of ensuring greater selectivity and more sustainability in these fisheries without losing their economic viability, such as adequacy of fishing nets and the use of bycatch reduction devices (BRD).Several BRD models have been developed and tested in different types of environments worldwide, many of which are summarized in the study by Broadhurst (2000).Thus, studies on fishing technology aiming at minimizing the capture of endangered species are essential for biodiversity maintenance.
The importance of the zoogeographic province of Argentina in the diversity of marine and estuarine fish fauna of Southern Brazil was evidenced in two other studies carried out in the Laje de Santos Marine State Park (Luiz Jr et al. 2008) and in the Paranaguá estuarine complex (Passos et al. 2012).The similarity in species composition was low (<50%) due to the different types of environments (rocky reefs, continental shelf and estuary).Totally, 427 species were observed, out of which 46 species (10.77%) are endemic to zoogeographic province of Argentina, being the fourth geographic distribution with the highest number of species, only behind the Western Atlantic with 169 species (39.58%), circumtropical with 52 species (12.18%) and trans-Atlantic with 50 species (11.71%).There was higher rate of endemism in the zoogeographic province of Argentina among marine demersal species (14.29%), followed by estuarine (10.95%) and reef (4.69%) species.
Based on the results of this work, we highlight the need for studies addressing other aspects of exploited communities, such as diversity analysis, spatial and seasonal distribution, as well as on impacts on explored demersal fishes, such as types of fishing, pollution, degradation of coastal areas and the introduction of exotic species.

Figure 1 .
Figure 1.Areas of legal practice of pair trawling fishing in the State of São Paulo (Espírito Santo to Rio Grande do Sul).The study area is highlighted in black.

Table 1 .
Distribution of the number of fishing operations (N) and percentage (%) in relation to the study period.

Table 2 .
Ichthyofauna caught by the pair trawling fleet of the state of São Paulo, Dajoz scale (DS): Co = constant, Ac = accessory, Ad = accidental; geographic distribution (GD): CT = circumtropical, TA = Trans-Atlantic (both sides of the Atlantic), WA = Western Atlantic (Northern and Southwestern Atlantic), SWA = Southern West Atlantic (from northern Brazil to Argentina), SSWA = Southern South West Atlantic (species with affinity to temperate areas occurring from Argentina and Uruguay to southern Brazil), Ca = Caribbean (from Florida to Venezuela), Br = Brazilian Province (the area between the Orinoco Delta in Venezuela and Santa Catarina in Brazil) and EP = Eastern Pacific; conservation status in the IUCN Red List (IUCN 2017), in the Brazilian list (MMA 2014): X = Not Evaluated; LC = Least Concern; DD = Data Deficient; VU = Vulnerable; NT = Near-Threatened; END = Endangered, CR = Critically Endangered; vouchers.