AVERAGE LENGTH Decrease in the Rapid decrease in Multi-species, Pros: easy, cheap metric to assess size of unfished the size of habitat associated changes in the status of a fishery individuals outside individuals outside Average targets, not a good of the NTZ, in of the NTZ, in Length indicator for Cons: does not capture selectivity of the comparison to comparison to highly mobile fishery, or is fishing is prosecuted in previous years previous years targets nursery grounds Catch Curve Finfish (groupers, FISHING MORTALITY (F) snapper, grunts, Mean Length etc.), and (Lbar) Pros: mortality rates are critical for invertebrates with Bounded determining abundance of fish determinant F/M <1 (F is Mean Length populations growth (lobsters, fishing mortality, Mortality F=2M crabs). Use with M is natural Estimator Cons: all of the models assume care for targets mortality) equilibrium conditions. Most of these that have methods only reflect fish that have deterministic Mean Weight recruited to a fishery and does not reflect growth and Mortality Fishery the full age structure of a stock. episodic Estimator Dependent recruitment. Finfish (groupers, Composition slow growing SPAWNING POTENTIAL RATIO snapper, grunts, Survey species, M/k< 1 (SPR) etc.), and (grouper) SPR > slow growing invertebrates with 40% (M is natural species, M/k< 1 Pros: can be used with fishery determinant mortality, k is von (grouper) SPR independent and dependent data. growth (lobsters, Bertalanffy growth <40% Length-based crabs). Use with rate) SPR (LBSPR) Cons: Assumes equilibrium conditions care for targets fast growing and a index based on the early life that have fast growing species, M/k >1 history of a fish, it must be remembered deterministic species, M/k >1 (lobster) SPR <20% that many things can happen to the fish growth and (lobster) SPR before they are large enough to harvest. episodic =20% recruitment.
AVERAGE LENGTH Pros: easy, cheap metric to assess changes in the status of a fishery Cons: does not capture selectivity of the fishery, or is fishing is prosecuted in nursery grounds Decrease in the size of unfished individuals outside of the NTZ, in comparison to previous years Rapid decrease in the size of individuals outside of the NTZ, in comparison to previous years Average Length Multi-species, habitat associated targets, not a good indicator for highly mobile targets Fishery Dependent Survey FISHING MORTALITY (F) Pros: mortality rates are critical for determining abundance of fish populations Cons: all of the models assume equilibrium conditions. Most of these methods only reflect fish that have recruited to a fishery and does not reflect the full age structure of a stock. F/M <1 (F is fishing mortality, M is natural mortality) F=2M Catch Curve Finfish (groupers, snapper, grunts, etc.), and invertebrates with determinant growth (lobsters, crabs). Use with care for targets that have deterministic growth and episodic recruitment. Mean Length (Lbar) Bounded Mean Length Mortality Estimator Mean Weight Mortality Estimator SPAWNING POTENTIAL RATIO (SPR) Pros: can be used with fishery independent and dependent data. Cons: Assumes equilibrium conditions and a index based on the early life history of a fish, it must be remembered that many things can happen to the fish before they are large enough to harvest. slow growing species, M/k< 1 (grouper) SPR > 40% (M is natural mortality, k is von Bertalanffy growth rate) fast growing species, M/k >1 (lobster) SPR =20% slow growing species, M/k< 1 (grouper) SPR <40% fast growing species, M/k >1 (lobster) SPR <20% Length-based SPR (LBSPR) Finfish (groupers, snapper, grunts, etc.), and invertebrates with determinant growth (lobsters, crabs). Use with care for targets that have deterministic growth and episodic recruitment. Composition
Guidance%20for%20PIs%20RPs%20and%20HCRs_1.docx