252
et al. 2008). Sharks, skates, and rays composes the subclass Elasmobranchii (i.e.
elasmobranchs) currently comprising a group of approximately 1150 species
(Nelson 2006). Due to the development of a differentiated mandibular apparatus
and an accurate sensorial system, elasmobranchs became predominantly predators,
usually occupying higher or intermediate trophic levels (Camhi et al. 1998; Musick
1999). Therefore, they usually occur in relatively smaller abundances than species
of lower trophic levels (Walker 1998; Stevens et al. 2000) though playing an important role in maintaining marine ecosystems healthy (e.g. control of genetic quality
of populations, Holden 1974).
Elasmobranchs are long lived species characterized by low productivity rates
which generally implies in small litters, slow growth rates and late onset of sexual
maturity (Cortes et al. 2002; Garcia et al. 2008). These features are associated to
high vulnerability and extinction risk, whereas populations have limited recovery
capacity following overexploitation by fishing and even habitat losses and/or degradation (Smith et al. 1998; Stobutzki et al. 2002). A great diversity of elasmobranchs
has been explored by modern fisheries, regularly caught as by-catch (i.e incidental)
and more recently (>1990) as target, especially in longline, trawl and gill nets fisheries (Bonfil 1994; Baum et al. 2003; Barreto et al. 2016).
Population declines have been documented for several elasmobranchs species
worldwide (Hutchings 2000; Baum et al. 2003; Ferretti et al. 2010; Clarke et al.
2011; Barreto et al. 2016). There are well-documented cases of elasmobranchs populations that collapsed such as Lamna nasus in the North Atlantic; Galeorhinus
galeus in California and Australia; Cetorhinus maximus in England; Squalus acanthias in the North Sea and British Columbia; Pristis pectinata in Florida and
Louisiana, and large coastal sharks off the west coast of the United States, such as
Carcharias taurus and Carcharhinus obscurus (International Union for Conservation
of Nature – IUCN). The IUCN reports that approximately 30% of elasmobranchs
are threatened with extinction (Dulvy et al. 2014). Worryingly, 47% of extant species do not have minimal information to be evaluated under the IUCN classifying
system (Dulvy et al. 2014; Mace et al. 2008).
10.2 Elasmobranch Fisheries in Brazil
South Atlantic fisheries, specifically assessed from Brazil during the late 1990s
reached critical levels for spinny angel shark Squatina guggenheim, hidden angel
shark S. occulta; Brazilian guitarfish Rhinobatos horkelli, scalloped hammerhead
shark Sphyrna lewini, sand tiger shark Carcharias taurus, school shark Galeorhinus
galeus and narrownose smooth-hound Mustelus schmitti (Vooren 1997; Lessa et al.
1999). More recently (between 2010 and 2012), Brazil reassessed elasmobranchs
following the IUCN’s system, resulting in 33% of species in threatened categories
(VU = 19; EN = 8; CR = 28), and 36% for which the available information did not
allow for any sort of categorization (i.e. Data Deficient-DD) (ICMBio 2016). This
result overcomes the global rate of threatened species (approximately 25% – Dulvy
et al. 2014).
H. Bornatowski et al.
et al. 2008). Sharks, skates, and rays composes the subclass Elasmobranchii (i.e.
elasmobranchs) currently comprising a group of approximately 1150 species
(Nelson 2006). Due to the development of a differentiated mandibular apparatus
and an accurate sensorial system, elasmobranchs became predominantly predators,
usually occupying higher or intermediate trophic levels (Camhi et al. 1998; Musick
1999). Therefore, they usually occur in relatively smaller abundances than species
of lower trophic levels (Walker 1998; Stevens et al. 2000) though playing an important role in maintaining marine ecosystems healthy (e.g. control of genetic quality
of populations, Holden 1974).
Elasmobranchs are long lived species characterized by low productivity rates
which generally implies in small litters, slow growth rates and late onset of sexual
maturity (Cortes et al. 2002; Garcia et al. 2008). These features are associated to
high vulnerability and extinction risk, whereas populations have limited recovery
capacity following overexploitation by fishing and even habitat losses and/or degradation (Smith et al. 1998; Stobutzki et al. 2002). A great diversity of elasmobranchs
has been explored by modern fisheries, regularly caught as by-catch (i.e incidental)
and more recently (>1990) as target, especially in longline, trawl and gill nets fisheries (Bonfil 1994; Baum et al. 2003; Barreto et al. 2016).
Population declines have been documented for several elasmobranchs species
worldwide (Hutchings 2000; Baum et al. 2003; Ferretti et al. 2010; Clarke et al.
2011; Barreto et al. 2016). There are well-documented cases of elasmobranchs populations that collapsed such as Lamna nasus in the North Atlantic; Galeorhinus
galeus in California and Australia; Cetorhinus maximus in England; Squalus acanthias in the North Sea and British Columbia; Pristis pectinata in Florida and
Louisiana, and large coastal sharks off the west coast of the United States, such as
Carcharias taurus and Carcharhinus obscurus (International Union for Conservation
of Nature – IUCN). The IUCN reports that approximately 30% of elasmobranchs
are threatened with extinction (Dulvy et al. 2014). Worryingly, 47% of extant species do not have minimal information to be evaluated under the IUCN classifying
system (Dulvy et al. 2014; Mace et al. 2008).
10.2 Elasmobranch Fisheries in Brazil
South Atlantic fisheries, specifically assessed from Brazil during the late 1990s
reached critical levels for spinny angel shark Squatina guggenheim, hidden angel
shark S. occulta; Brazilian guitarfish Rhinobatos horkelli, scalloped hammerhead
shark Sphyrna lewini, sand tiger shark Carcharias taurus, school shark Galeorhinus
galeus and narrownose smooth-hound Mustelus schmitti (Vooren 1997; Lessa et al.
1999). More recently (between 2010 and 2012), Brazil reassessed elasmobranchs
following the IUCN’s system, resulting in 33% of species in threatened categories
(VU = 19; EN = 8; CR = 28), and 36% for which the available information did not
allow for any sort of categorization (i.e. Data Deficient-DD) (ICMBio 2016). This
result overcomes the global rate of threatened species (approximately 25% – Dulvy
et al. 2014).
H. Bornatowski et al.