Judged:
2
Predation, competition, and the recovery of
overexploited fish stocks in marine reserves
Marissa L. Baskett, Mary Yoklavich, and Milton S. Love (UCSB)
The existence of alternative states in communities
with intraguild predation, including the specific case in which competition and predation occur during different life history stages, means that the final state of the communities depends on which species dominates initially
These co-occurring species can interact when the juveniles of the larger species compete with the smaller species, as well as when the adults of the larger species prey on the smaller species. The smaller rockfish species represents one component of the larger species’varied diet; for example, yelloweye rockfish prey on Pacific herring (Clupea pallasii), Pacific sand lance (Ammodytes hexapterus), flatfishes, shrimps, and crabs, as well as smaller rockfishes (Love et al. 2002).
Before anthropogenic disturbance dominated the system, predation and competition pressure from the larger species likely kept the smaller species at low population densities, except in suboptimal habitats not occupied by larger species.
Now overfishing has substantially reduced population densities of the larger species, thereby releasing predation and competition pressures and likely causing a subsequent explosion in the smaller species’ populations in the higher quality habitat previously dominated by the larger species.
From surveys of rock habitats in deep water off California and Oregon, larger individuals of several overfished species of rockfishes, such as canary (Sebastes pinniger) and bocaccio
(Sebastes paucispinis), as well as yelloweye rockfish, are in low numbers or almost absent, whereas dwarf species such as halfbanded (Sebastes semicinctus) and squarespot (Sebastes hopkinsi) rockfishes, as well as pygmy rockfishes,
dominate the fish assemblages in these areas (Stein et al. 1992; Yoklavich et al. 2000, 2002).
Though fisheries closures are implemented in response to overfishing, competition between expanded populations of the smaller species and juveniles of the larger species may slow or prevent the overfished larger species from recovering (MacCall 2002; Mangel and Levin 2005).
Stock assessments and rebuilding plans for overfished populations currently use single-species models (Punt 2003), which ignore the interactions described above.
Regardless of whether species interactions cause shifts to alternative stable states or simply slow recovery following anthropogenic disturbance, the outcome is a reason for concern (Knowlton 2004), and management decisions may need to account for community interactions.
Although the general response of marine communities to reserve establishment can be an increase in numbers and biomass (Halpern and Warner 2002), the combination of historical
overfishing and community interactions may impede recovery of specific species with reserve establishment.
http://www.lovelab.id.ucsb.edu/Baskett_et_al.... ARE YOU CERTAIN YOU REVIEWED THE MARINE PROTECTED AREAS SCIENCE, JOHN PEARSE?
APPEARS THAT YOU MISSED THIS ONE FROM UCSB...
BTW, OVERFISHING WAS FROM COMMERCIAL TYPE FISHING THAT DRAGS A NET OVER THE BOTTOM AND DESTROYS THEIR (FISH) HABITAT...SO you COULD HAVE CHEAP FISH IN THE GROCERY STORE! BRILLIANT!!
DON'T TAR RECREATIONAL FISHING AS PART OF THE OVERFISHING PROBLEM.
WANT FISH? ALABAMA HAS LESS THAN 5% OF THE U.S. GULF COAST AND OVER 33% OF THE RECREATIONALLY LANDED ROCK FISH ON THAT COAST.
THE ECONOMIC BENEFITS OF THEIR BUILDING UNDERWATER STRUCTURE IS HUGE FOR ALABAMA AND IS EXPANDING!!!
WHAT CAN YOUR MPA's POINT TO EXCEPT DISAGREEING RESEARCHERS?