Desenvolvimento tecnológico na captura de recursos demersais de profundidade na Zona Econômica Excluisva (ZEE) Norte do Brasil

Abstract

The Brazilian northern coast presents itself as a demersal resource-rich area, underscored by high abundance and species diversity in the area between Orange Cape (Amapá State) and the Parnaíba river’s mouth on the Maranhão/Piauí states border. The family Aristeidae is comprised of twenty-six species in nine genera, among which at least five species of three genera (Aristeus, Aristaeopsis and Aristaeomorpha) hold economic importance and presently sustain targeted commercial fisheries. The fishing trips were carried out on the continental upper slope and shelf off norther in Brazil, by trawling hauls in the 236 – 1,246 meters depth range, between latitudinal positions 01º 23’N - 05º 09’N. As concerns the surveying of deep-water shrimps, the primary source of data for this Thesis, information was obtained for two main variables, namely trawling depth and yield index as measured by the catch per unit effort, resulting in an abundance index as kg per trawling hour”. Such data were produced by a number of otter trawlnets, namely twin nets (GEM), all-purpose (POL) and unique (UNI), to which oval (OV)- and rectangular (RET)-shaped otter doors were attached. The virg n biomass (B) was estimated by the Swept Area Method, specially meant for demersal/benthonic species. Throughout the prospective voyages 71 different species were caught and made up a 106,974 kg biomass, with the following shares per species group: bony fish (67.1%), cartilaginous fish (4.3%), crustaceans (25.2%) and mollusks (3.9%). The trawlnets. Irrespective of the type, operated in very similar depth ranges over the three species, averaging about 740 m. No variation trend was identified between yield index and depth, as shown by the Spearman’s non-parametric correlation test, but for the whole set of nets a pattern emerges as to the clustering of values in the 700 – 800 meter. A comparison among nine “net/otter door” groups through the Kruskal-Wallis test, yielded a value of H = 182.07 (P <0.01). The discriminatory Dunn’s test bears out this high significance of H and shows that, among 36 comparisons, only three proved to be non-significant, namely POLOV-UN2RET (Q = 0.224), UNIOV-UN3OV (Q = 1.803) e UNIOV-UN3RET (Q = 2.591). From a technological viewpoint, one must use those trawlnet/otter door sets in the following decreasing order, by species - “Carabineiro”: GEM, UN13-0V, UNI-OV, UNI3-RET, UNI-RET, UNI2-OV, POL-OV, UNI2-RET, POL-RET; “Alistado”: GEM, UNI-OV, UNI2-OV, POL-RET, UNI3-RET, UNI-RET, UNI3-OV, POL-OV, UNI2-RET; “Chatim”: UNI3-RET, UNI3-OV, UNI2-0V, UNI-OV, GEM, UNI-RET, UNI2-RET, POL-OV, POL-RET. The biomass sustainable 10 values, estimated for a coefficient of trawling efficiency, p = 0.7, were: “Carabineiro” = 674 t; “Alistado” = 363 t ; “Chatim” = 157 t; Overall = 1.194 t. Even whether the exploitation of deep-water shrimp, snook and giant squid is found to be a promising commercial entreprise, public and private investments over those new fishing resources must be closely evaluated and planed for, and their projects soundly based on reliable data.