AVERAGE LENGTH All targets, Pros: easy, cheap metric to assess especially changes in the status of a fishery when nearshore targets. stratified across sampling unit (gear, In an ideal Decrease in average efforts, fishing zone) Increase in average Average scenario an length or mature length Length historic record of adults Cons: With little to no historical average length information on the length of the catch or would be used to with no information on gear selectivity, compare current the average length could biases the to past estimates. expected potential size distribution. FROESE INDICATORS 100% of catch – <80% of catch – optimal optimal All fish and Pros: proved estimate of the status of the invertebrate target Froese stock, in comparison to sustainability < 10% of the catch < 20% of the catch with known Sustainability reference points are megaspawners are megaspawners Indicators Cons: does not contribute to biomass 90% of the catch 50% of the catch are relationships sustainability reference points are mature adults mature adults CPUE Catch Pros: can be used to infer population Reporting trends of an exploited stock. Standardized Rapidly Decreasing All targets that do System & time series of CPUE are often regarded as CPUE, previous Catch Trends not have high Boat indices of abundance. Stable CPUE year or in selectivity of comparison to habitat Site Cons: seldom proportional to abundance running average stratification. Survey history and an entire geographic range. Can be skewed, depending on sampling regime. May have species-specific biases.
AVERAGE LENGTH Pros: easy, cheap metric to assess changes in the status of a fishery when stratified across sampling unit (gear, efforts, fishing zone) Cons: With little to no historical information on the length of the catch or with no information on gear selectivity, the average length could biases the expected potential size distribution. Increase in average length Decrease in average length or mature adults Average Length All targets, especially nearshore targets. In an ideal scenario an historic record of average length would be used to compare current to past estimates. FROESE INDICATORS Pros: proved estimate of the status of the stock, in comparison to sustainability reference points Cons: does not contribute to biomass sustainability reference points 100% of catch – optimal < 10% of the catch are megaspawners 90% of the catch are mature adults <80% of catch – optimal < 20% of the catch are megaspawners 50% of the catch are mature adults Froese Sustainability Indicators All fish and invertebrate target with known relationships Catch Reporting System & Boat Site Survey CPUE Pros: can be used to infer population trends of an exploited stock. Standardized time series of CPUE are often regarded as indices of abundance. Cons: seldom proportional to abundance history and an entire geographic range. Can be skewed, depending on sampling regime. May have species-specific biases. Stable CPUE Rapidly Decreasing CPUE, previous year or in comparison to running average Catch Trends All targets that do not have high selectivity of habitat stratification.
Guidance%20for%20PIs%20RPs%20and%20HCRs_1.docx