Joint effects of larval dispersal, population regulation, marine reserve design, and exploitation on production and recruitment in the Caribbean spiny lobster
Wt. Stockhausen et al., Joint effects of larval dispersal, population regulation, marine reserve design, and exploitation on production and recruitment in the Caribbean spiny lobster, B MARIN SCI, 66(3), 2000, pp. 957-990
A spatially explicit population-dynamics model for the Caribbean spiny lobs
ter (Panulirus argus) in Exuma Sound Bahamas, was used to investigate the j
oint effects of marine reserve design and larval dispersal via hydrodynamic
currents on an exploited benthic invertebrate. The effects of three hydrod
ynamic scenarios tone diffusion-only and two advection-diffusion cases), on
e exploitation level, and 28 reserve configurations (7 sizes x 4 locations)
on catch and larval production were simulated. The diffusion-only scenario
represented the condition in which settlement did not vary substantially o
ver broad spatial scales; in contrast, the advection-diffusion scenarios re
presented realistic hydrodynamic patterns and :introduced broad spatial var
iation. Both advection-diffusion scenarios were based on empirical measurem
ents of near-surface flow in Exuma Sound. Catches were sensitive to interac
tions between reserve configuration and pattern of larval dispersal. A give
n reserve configuration led to enhancement or decline in catch, depending o
n the hydrodynamic scenario, reserve size, and reserve location. Larval pro
duction increased linearly with reserve size, when size was expressed as th
e population fraction initially protected by the reserve, but when reserve
size was expressed as the fraction of coastline protected, larval productio
n decreased for some reserve configurations under the two advection-diffusi
on hydrodynamic scenarios. Use of a simple reserve-design rule (e.g., prote
ct 20% of a coast) would in the latter cases, lead to a false sense of secu
rity, thereby endangering-not protecting-exploited stocks. The optimal desi
gn of marine reserves therefore requires attention to the joint effects of
larval dispersal, reserve location, and reserve size on fishery yield and r
ecruitment.