SEDAR 49 Assessment Review Workshop: Gulf of Mexico ABC Control Rule and DLM Theory in a Nutshell November 1, 2016 Jeff Isely, Skyler Sagarese, Matthew Smith Southeast Fisheries Science Center, Sustainable Fisheries Division, Miami, FL

Gulf of Mexico ABC Control Rule Tier 1: A quantitative assessment provides both an estimate of OFL based on MSY or its proxy, and a probability density function of OFL that reflects scientific uncertainty.

Gulf of Mexico ABC Control Rule Tier 2: An assessment exists but does not provide an estimate of MSY or its proxy. Instead, the assessment provides a measure of OFL based on alternative methodology. Additionally, a probability density function can be calculated to estimate scientific uncertainty in the model-derived OFL measure. This density function can be used to approximate the probability of exceeding the OFL, thus providing a buffer between the OFL and ABC.

Gulf of Mexico ABC Control Rule Tier 3: No assessment is available, but landings data exist. The probability of exceeding the OFL in a given year can be approximated from the variance about the mean of recent landings to produce a buffer between the OFL and ABC. Recent historical (reference period) landings are without trend, landings are small relative to stock biomass, or the stock is unlikely to undergo overfishing if future landings are equal to or moderately higher than the mean of recent landings. For stock complexes, the determination of whether a stock complex is in Tier 3a or 3b will be made using all the information available, including stock specific catch trends.

Gulf of Mexico ABC Control Rule Tier 3 Data poor species Not enough information to conduct a traditional assessment OFL is based on best scientific information available Base stock status on expert opinion Base management on stock status Landings only Establish a reference period

Gulf of Mexico ABC Control Rule Tier 3A Based on expert evaluation of best scientific information available Assumes: Recent historical landings (reference period) are without trend Landings are small relative to stock biomass Stock is unlikely to undergo overfishing if future landings slightly exceed mean of recent landings OFL = Mean of reference period landings + 2SD ABC = Mean + 1SD* * Depending on risk of overfishing

Gulf of Mexico ABC Control Rule Tier 3B Based on expert evaluation of best scientific information available Assumes recent historical landings (reference period) may be unsustainable. OFL = Mean of reference period landings ABC = % of Mean of reference period landings

Data Limited Approach Catch only Recent Landing or reference period No Data Limited Approach (given GOM ABC Control Rule) Existing ABC Control Rule

Catch plus additional information Data Limited Approach Catch plus additional information Adjust OFL and ABC based on Landings and trends Specific models in the toolbox consider CPUE Annual Mean Length Annual Mean Age Life History Growth

Data Limited Approach Catch and Index CPUE Annual Mean Length Annual Mean Age Life History

Data Limited Model Approach Compare Recent Index to Reference Index Adjust OFL and ABC based on index

SEDAR49 Approach Catch only Maintain status quo for Tier3A or Tier3B ABC Control Rule If Index Adjust based on Index