The freshwater artisanal fishery of Patos Lagoon

Abstract

In this study data relative to the fishery in the freshwater area of the Patos Lagoon are analysed, and the dynamics, fishing gears used and catches evaluated. The results reveal the existence of two fishery strategies: forbidden mesh size gillnets (FMG; <35 mm; square measure) and allowed mesh size gillnets (AMG; ≥35 mm; square measure). In total, 31 species were caught (AMG = 27 and FMG = 24), but selectivity due to mesh size was significant (P < 0·001). The FMG may be very harmful since it captures individuals of most species below size at first maturity, including the target species, the armoured catfish Loricariichthys anus (61% of the total catch). In addition, this gear is used throughout the year, including the closed season (CS; November to January), when the target species is reproducing. Target species for the AMG are larger in size, comprising mainly the mullet Mugil liza, the marine catfish Genidens barbus and the whitemouth croaker Micropogonias furnieri. AMS gillnets were not used during the CS. The use of FMG reveals the need for effective fishery law enforcement and the need for additional studies to assess the status of populations of the exploited species.

How Far Upstream: A Review of Estuary-Fresh Water Fish Movements in a Large Neotropical Basin

“…First, the species does not move toward the rivers forming the Patos Basin, as no specimens were caught in the extensive Sinos River sampling program, in agreement with its absence from museum collections. Unfortunately, the smallest mesh size used by Ceni et al (2016) was 35 mm (adjacent knots), and direct comparison of the species size profile with the present samples (taken using mesh sizes from 15 mm) is not possible. Nevertheless, it is clear that M. furnieri could be present in the northern Patos Lagoon and Guaíba Lake during all months of the year, from juveniles to adults, although mostly juveniles occur in southern Guaíba Lake in winter.…”

“…Lucena et al (1994), from monthly samples taken with a beach seine in southern Guaíba Lake, recorded only two captures of M. furnieri in autumn. In a more-recent sampling program, using surface and bottom gillnets (adjacent knots: 35, 40, 45, 50, 55, 60 and 65 mm), Ceni et al (2016) captured M. furnieri in the northern Patos Lagoon in the size range of 10-55 cm (total length). The species was present year-round and was 3-4-fold more abundant from August to October.…”

“…A general pattern of higher winter abundance in northern fresh waters prior to a spring spawning in the estuary suggests a more-complex migration pattern. Also, the presence of adult M. furnieri in the northern Patos Lagoon year-round (Ceni et al, 2016) suggests a more intricate pattern of habitat occupation (life-style polymorphism), with adult individuals not returning to the sea after reproducing, and perhaps spending their entire lives in fresh to brackish waters. Analysis of the Sr:Ca and Ba:Ca ratios is needed to resolve these questions, and a full understanding of M. furnieri life history is still to come.…”

Coastal zone use and migratory behaviour of the southern population of Mugil liza in Brazil

“…Juveniles of M. liza are much more abundant in the estuary (45 individuals 100 m −2 ) than in the freshwater portion of the lagoon (1.2 individuals 100 m −2 ) (Vieira et al, 2010). However, the occurrence of M. liza individuals and even M. liza fisheries in the freshwater portion of the Patos Lagoon is well known (Ceni et al, 2016;Milani & Fontoura, 2007). These results reinforce the idea that species behaviour is more variable than previously thought (Chapman et al, 2012).…”

Defining the reproductive period of freshwater fish species using the Gonadosomatic Index: a proposed protocol applied to ten species of the Patos Lagoon basin

“…Although the freshwater fish species of the Patos Lagoon basin are relatively well known taxonomically, with more than 200 recorded limnetic species (Malabarba, 1989;Reis et al, 2003;Bertaco et al, 2016;Fontoura et al, 2016), information concerning reproductive aspects of these species is still needed. Although recent reviews have treated aspects of the conservation and fishery (Ceni et al, 2016) of the Patos basin, the only general overview of the reproductive biology of fish species was by Marques et al (2007), who estimated the size at first maturity for some dominant species.…”