communities. There are several bottom trawling fisheries in Argentina. Currently,
three fisheries have by-catch monitoring programs in order to assess the condition
of the disturbed bottoms; these are the red shrimp fishery and the Patagonian and
Tehuelche scallop fisheries.
The red shrimp (Pleoticus muelleri) fishery has operated in SJOG since 1980.
Only 20 % of the species found in the benthic community are retained as incidental
catch during the fishery trawls. Echinoderms, together with crustaceans and mollusks,
are the main groups of by-catch. Diplasterias brandti, Henricia obesa, Pseudechinus
magellanicus, Arbacia dufresnii, Austrocidaris canaliculata, Trypilaster philippi,
Hemioedema spectabilis and Gorgonocephalus chilensis are the echinoderm species
caught by the shrimp trawl (Roux et al. 2007); Diplasterias brandti being the most
frequent. The benthic communities subjected to trawling partially maintain their
structure, species richness and spatial distribution (Roux 2008).
The most productive Patagonian scallop (Zygochlamys patagonica) fishing
grounds in Argentina are associated with the shelf-break frontal system and have
been exploited since 1996. Several studies on incidental catches show that brittle
stars, sea stars and sea urchins are the dominant taxa in most of the scallop beds;
reaching 86 % of the total catch in some of them (Bremec et al. 2006, Escolar et al.
2007; Schejter et al. 2008). The biomass of echinoderms as bycatch increased from
1997 to 2002 in sites with high fishing activity (Escolar et al. 2009). Because many
echinoderms are predators, they could be favored by fishery discards. In addition,
an increase in biomass of Ophiactis asperula (detritivore) was recorded in
intensively trawled sites, while Ophiacantha vivipara and Sterechinus agassizii
decreased (Schejter et al. 2008). Although relative abundances of some taxa varied
over time, no loss of species has been recorded in the Patagonian scallop community since the start of the fishery (Bremec et al. 2008).
The Tehuelche scallop (Aequipecten tehuelchus) fishery in SMG is the main
coastal bivalve fishery in Argentina. This fishery started in 1969 and was closed for
ten years from 1973 to 1983 (Ciocco et al. 2006). Impact studies on biodiversity
reported five species of echinoderms (Arbacia dufresnii, Pseudechinus magellanicus, Tripylaster sp., Ophioplocus januarii and Cosmasterias lurida) as part of
incidental catches. The total density of echinoderms remained stable in sites
without fishing activity and increased in sites that were intensively exploited until
2000; the dominant species were A. dufresnii, P. magellanicus and O. januarii.
In contrast, echinoderm density had been reduced at sites subjected to intensive
and continuous fishing activity. Patches of A. dufresnii and P. magellanicus were
depleted in these fishing grounds (Morsán 2009).
11.6 Concluding Remarks
Until recently studies on echinoderms in Argentina were very limited. During the
last century Bernasconi’s publications were the principal references for this
phylum. In the last ten years there was an increase of studies on the echinoderm
388
M. I. Brogger et al.
three fisheries have by-catch monitoring programs in order to assess the condition
of the disturbed bottoms; these are the red shrimp fishery and the Patagonian and
Tehuelche scallop fisheries.
The red shrimp (Pleoticus muelleri) fishery has operated in SJOG since 1980.
Only 20 % of the species found in the benthic community are retained as incidental
catch during the fishery trawls. Echinoderms, together with crustaceans and mollusks,
are the main groups of by-catch. Diplasterias brandti, Henricia obesa, Pseudechinus
magellanicus, Arbacia dufresnii, Austrocidaris canaliculata, Trypilaster philippi,
Hemioedema spectabilis and Gorgonocephalus chilensis are the echinoderm species
caught by the shrimp trawl (Roux et al. 2007); Diplasterias brandti being the most
frequent. The benthic communities subjected to trawling partially maintain their
structure, species richness and spatial distribution (Roux 2008).
The most productive Patagonian scallop (Zygochlamys patagonica) fishing
grounds in Argentina are associated with the shelf-break frontal system and have
been exploited since 1996. Several studies on incidental catches show that brittle
stars, sea stars and sea urchins are the dominant taxa in most of the scallop beds;
reaching 86 % of the total catch in some of them (Bremec et al. 2006, Escolar et al.
2007; Schejter et al. 2008). The biomass of echinoderms as bycatch increased from
1997 to 2002 in sites with high fishing activity (Escolar et al. 2009). Because many
echinoderms are predators, they could be favored by fishery discards. In addition,
an increase in biomass of Ophiactis asperula (detritivore) was recorded in
intensively trawled sites, while Ophiacantha vivipara and Sterechinus agassizii
decreased (Schejter et al. 2008). Although relative abundances of some taxa varied
over time, no loss of species has been recorded in the Patagonian scallop community since the start of the fishery (Bremec et al. 2008).
The Tehuelche scallop (Aequipecten tehuelchus) fishery in SMG is the main
coastal bivalve fishery in Argentina. This fishery started in 1969 and was closed for
ten years from 1973 to 1983 (Ciocco et al. 2006). Impact studies on biodiversity
reported five species of echinoderms (Arbacia dufresnii, Pseudechinus magellanicus, Tripylaster sp., Ophioplocus januarii and Cosmasterias lurida) as part of
incidental catches. The total density of echinoderms remained stable in sites
without fishing activity and increased in sites that were intensively exploited until
2000; the dominant species were A. dufresnii, P. magellanicus and O. januarii.
In contrast, echinoderm density had been reduced at sites subjected to intensive
and continuous fishing activity. Patches of A. dufresnii and P. magellanicus were
depleted in these fishing grounds (Morsán 2009).
11.6 Concluding Remarks
Until recently studies on echinoderms in Argentina were very limited. During the
last century Bernasconi’s publications were the principal references for this
phylum. In the last ten years there was an increase of studies on the echinoderm
388
M. I. Brogger et al.