The IUCN/SSC Shark Specialist Group
Shark News 14: March 2002
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Bycatch of Sharks and Rays in the Deep Sea Crustacean Fishery off the Chilean Coast
Enzo Acuña & Juan C. Villarroel, Universidad Católica del Norte, Chile
The crustacean fishery for the red squat lobster Pleuroncodes monodon,
the yellow squat lobster Cervimunida johni and deep sea shrimp
Heterocarpus reedi, is a very important commercial fishing activity off
northern Chile. This is a bottom trawl fishery that occurs close to the
shelf break and into the upper slope, between 180-500 m depth, with
each of the three crustacean species being more abundant from
shallower to deeper waters in the following order: the red squat lobster,
the yellow squat lobster and deep sea shrimp. The bycatch of this
fishery includes several teleost and chondrichthyan fish species. Fifty
one species of sharks and thirty seven species of rays have been
recorded for Chilean waters by Pequeño (1989, 1997).
The most abundant bycatch species in this fishery is the common
hake Merluccius gayi, which contributes 40-50% of the relative
abundance by weight of the bycatch. The chondrichthyan species are
far less abundant with sharks, rays and chimaeras accounting for less
than 10% of the total relative abundance by weight (Table 1).
A monitoring program of this fishery began in mid 1997, in the area
between 26° and 36°S off Chile, and since then ten shark species, four
ray species and one chimaerid have been recorded. The greatest
diversity of bycatch has been found in the deep sea shrimp catches,
which is usually deeper than the two squat lobster species. (Table 1).
The percentage by weight of chondrichthyan species increases
with depth, with only two shark and one ray species present in the red
squat lobster fishing grounds and four shark and three ray species in the
yellow squat lobster fishing grounds, representing in both cases less
than 1% by weight of the bycatch. In the deep sea shrimp fishing
grounds ten shark, four ray and one chimaerid species are caught,
comprising around 10% of the bycatch by weight. However, only two
shark species are relatively important in the bycatch of the deep sea
shrimp fishing grounds: the hooktooth dogfish Aculeola nigra and the
dusky catshark Halaelurus canescens, each comprising less than 5% of
the bycatch (Table 1). With respect to the rays, only one species is
relatively important in the catches of the deep sea shrimp fishery: the
yellownose skate Dipturus chilensis (McEachran and Dunn 1998),
comprising less than 1% of the bycatch (Table 1).
This increase with depth seems to be a common trend, since a study
in the bycatch of deep-water bottom trawl fishery for orange roughy
between 800-1200m (Koslow et al. 1994) and orange roughy and
smooth oreo between 740-1503m (Wetherbee 2000) off New Zealand
and Australia, show more species and a larger percentage of deep sea
sharks in the bottom trawl captures at depths deeper than those of the
Northern Chilean crustacean fishery. A similar pattern was described
for rays by McEachran and Miyake (1990) which is consistent with our
findings.
The biological information available for these deep sea shark
species is scarce and has only recently been increasing due to this
study. Only a few papers regarding their trophic ecology are published
in the Chilean literature (Arancibia & Meléndez 1987). Recently,
Catalán (unpublished data) has begun studying the reproductive biology
of the two most important chondrichthyan bycatch species, Aculeola
nigra and Halaelurus canescens for his marine biology thesis from
specimens caught during this research program.
We would like to thank all who collaborated in the sampling
during the past four years, and the Crustacean Fishing Companies:
Agua Fría, Amancay, Isladamas, Pesca Marina and Socovel that
financed the Monitoring Program.
Table 1. Relative importance by weight (%) of teleost and chondrichthyan fish bycatch in the crustacean trawling fisheries from northern Chile. (Larger percentages are in bold).
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FISHERY
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Red Squat
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Yellow Squat
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Deep-sea
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Species
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Lobster
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Lobster
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Shrimp
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AGNATA
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<0.01
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<0.01
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0.1
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CHONDRICHTHYES
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0.12
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0.74
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9.28
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ELASMOBRANCHII
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SQUALOMOPRHII
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HEXANCHIFORMES
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Hexanchidae
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Hexanchus griseus
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-
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-
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<0.01
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SQUALIFORMES
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Echinorhinidae
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Echinorhinus cookei
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<0.01
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Squalidae
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Aculeola nigra
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0.1
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0.37
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4.55
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Centroscyllium granulatum
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-
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-
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0.15
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Centroscyllium nigrum
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-
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-
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0.60
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Centroscymnus crepidater
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-
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<0.01
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0.26
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Deania calcea
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<0.01
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<0.01
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Etmopterus granulosus
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-
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-
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0.01
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CARCHARHINIFORMES
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Scyliorhinidae
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Apristurus nasutus
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-
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-
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0.24
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Halaelurus canescens
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0.02
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0.28
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1.88
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TORPEDINIFORMES
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Torpedinidae
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Torpedo tremens
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-
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-
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0.09
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BATOIDEA
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RAJIFORMES
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Rajidae
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Dipturus chilensis
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-
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0.08
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0.89
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Pseudorajidae
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Sympterygia brevicaudata
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<0.01
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<0.01
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0.54
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Psammobatis scobina
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-
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<0.01
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0.07
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HOLOCEPHALII
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CHIMAERIFORMES
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Chimaeridae
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Hydrolagus macrophthalamus
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<0.01
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OSTEICHTHYES
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99.87
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99.25
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90.62
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References
Arancibia, H. and R. Meléndez. 1987. Alimentación de peces
concurrentes en la pesquería de Pleuroncodes monodon Milne
Edwards. Investigación Pesquera. (Chile) 34:113-128.
Koslow, J.A., C. M. Bulman and J. M. Lyle. 1994. The mid-slope
demersal fish community of southeastern Australia. Deep Sea
Research 41(1):113-141.
McEachran, J. D. and T. Miyake. 1990. Zoogeography and bathymetry
of Skates (Chondrichthyes: Rajoidei). In: Elasmobranchs as Living
Resources: Advances in the Biology, Ecology, Systematics, and the
Status of the Fisheries (H. L. Pratt Jr., S. H. Gruber and T. Taniuchi,
eds.). NOAA Technical Report 90:305-326.
McEachran, J. D. and K. Dunn. 1998. Phylogenetic Analysis of Skates,
a Morphologically Conservative Clade of Elasmobranchs
(Chondrichthyes: Rajidae). Copeia 2:271-290.
Meléndez, R. and D. Meneses. 1989. Tiburones del talud continental
recolectados entre Arica (18o19'S) e Isla Mocha (38o30'S), Chile.
Invest. Mar. Valparaíso 17:3-73.
Pequeño, G. 1989. Peces de Chile. Lista sistemática revisada y
comentada. Revista de Biología Marina Valparaíso 24:1-132.
Pequeño, G. 1997. Peces de Chile. Lista sistemática revisada y comentada:
addendum. Revista de Biología Marina y Oceanografía 32:77-94.
Wetherbee, B. 2000. Assemblage of deep-sea sharks on Chatham Rise,
New Zealand. Fish. Bull. 98:189-198.
Enzo Acuña
Departamento de Biología Marina,
Facultad de Ciencias del Mar, Universidad Católica del Norte,
Casilla 117, Coquimbo, Chile.
Fax: (56) 51 209812
Email: eacuna@ucn.cl
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