INVESTIGADORES
DIAZ DE ASTARLOA Juan Martin
artículos
Título:
From coexistence to competitive exclusion: can overfishing change the outcome of competition in skates (Chondrichthyes, Rajidae)?
Autor/es:
RUOCCO, N. L.; LUCIFORA, L.; DÍAZ DE ASTARLOA, J. M.; MENNI, ROBERTO C; GIBERTO, D.
Revista:
LATIN AMERICAN JOURNAL OF AQUATIC RESEARCH
Editorial:
UNIV CATOLICA DE VALPARAISO
Referencias:
Lugar: Valparaíso; Año: 2012 vol. 40 p. 102 - 112
ISSN:
0718-560X
Resumen:
Competition for food could be a major force driving changes in the community structure of
skates (Rajidae) subjected to fishing exploitation. Under this hypothesis, small skates are released from
competition with larger skates after fishing has depleted the larger species. Here, we compare the abundance
patterns of two sympatric skates with similar niches but different life histories, Bathyraja albomaculata (larger
and slow-reproducing) and Bathyraja macloviana (smaller and faster-reproducing), before (1971, 1978) and
after (1998-2004) a 108% increase in industrial bottom trawling on the southeastern South American shelf in
order to test the prediction that B. macloviana should competitively exclude B. albomaculata after the increase
in fishing mortality. In 1971 and 1978, there was no relationship between the abundance of both species,
indicating that they coexisted over large scales. In 1998-2004, the relationship between the abundances of
these skates was bell-shaped, indicating that both species increased in abundance at low densities until
peaking, after which B. albomaculata decreased when B. macloviana became more abundant, consistent with
resource competition. We tested whether food may be a potential limiting resource by comparing the diet of
both species. The two species consumed mostly polychaetes, differing only in the consumption of polychaetes
from the family Nephthyidae, which was much higher for B. macloviana. Bathyraja macloviana could replaceBathyraja albomaculata (larger
and slow-reproducing) and Bathyraja macloviana (smaller and faster-reproducing), before (1971, 1978) and
after (1998-2004) a 108% increase in industrial bottom trawling on the southeastern South American shelf in
order to test the prediction that B. macloviana should competitively exclude B. albomaculata after the increase
in fishing mortality. In 1971 and 1978, there was no relationship between the abundance of both species,
indicating that they coexisted over large scales. In 1998-2004, the relationship between the abundances of
these skates was bell-shaped, indicating that both species increased in abundance at low densities until
peaking, after which B. albomaculata decreased when B. macloviana became more abundant, consistent with
resource competition. We tested whether food may be a potential limiting resource by comparing the diet of
both species. The two species consumed mostly polychaetes, differing only in the consumption of polychaetes
from the family Nephthyidae, which was much higher for B. macloviana. Bathyraja macloviana could replaceBathyraja macloviana (smaller and faster-reproducing), before (1971, 1978) and
after (1998-2004) a 108% increase in industrial bottom trawling on the southeastern South American shelf in
order to test the prediction that B. macloviana should competitively exclude B. albomaculata after the increase
in fishing mortality. In 1971 and 1978, there was no relationship between the abundance of both species,
indicating that they coexisted over large scales. In 1998-2004, the relationship between the abundances of
these skates was bell-shaped, indicating that both species increased in abundance at low densities until
peaking, after which B. albomaculata decreased when B. macloviana became more abundant, consistent with
resource competition. We tested whether food may be a potential limiting resource by comparing the diet of
both species. The two species consumed mostly polychaetes, differing only in the consumption of polychaetes
from the family Nephthyidae, which was much higher for B. macloviana. Bathyraja macloviana could replaceB. macloviana should competitively exclude B. albomaculata after the increase
in fishing mortality. In 1971 and 1978, there was no relationship between the abundance of both species,
indicating that they coexisted over large scales. In 1998-2004, the relationship between the abundances of
these skates was bell-shaped, indicating that both species increased in abundance at low densities until
peaking, after which B. albomaculata decreased when B. macloviana became more abundant, consistent with
resource competition. We tested whether food may be a potential limiting resource by comparing the diet of
both species. The two species consumed mostly polychaetes, differing only in the consumption of polychaetes
from the family Nephthyidae, which was much higher for B. macloviana. Bathyraja macloviana could replaceB. albomaculata decreased when B. macloviana became more abundant, consistent with
resource competition. We tested whether food may be a potential limiting resource by comparing the diet of
both species. The two species consumed mostly polychaetes, differing only in the consumption of polychaetes
from the family Nephthyidae, which was much higher for B. macloviana. Bathyraja macloviana could replaceB. macloviana. Bathyraja macloviana could replace
B. albomaculata at high densities when food resources may become scarce. These results support the
hypothesis that competition release is an important factor explaining the changes in skate communities in
overexploited areas.at high densities when food resources may become scarce. These results support the
hypothesis that competition release is an important factor explaining the changes in skate communities in
overexploited areas.