“FORGOTTEN SIGNALS IN FISHERIES MANAGEMENT” By, Deepak George Pazhayamadom Department of Zoology, Ecology and Plant Science (ZEPS) University College Cork (UCC), Cork, Ireland Emer Rogan (Department of ZEPS, University College Cork) Ciaran Kelly (Fisheries Science Services, Marine Institute) Edward Codling (Lecturer in Mathematical Biology, University of Essex)

Fisheries Management (Traditional approach) DATA Fisheries Management (Alternative approach) SSB, F [Estimated Indicators] (Stock abundance and Exploitation) MODELS (Assumptions) Monitor with Reference Limits (Acceptable, Precautionary, Limit) Regulate with output controls HCR (Eg: TAC) Other measures (Eg: Effort) Next Year Limit Precautionary Acceptable Statistical Process Control [Signal Detection Method] Statistical Signals [Stock Indicators]

Indicator Correlation Spawning Stock Biomass Year Catch Numbers Age Correlation = Degree of relationship 0.7 = Good 0.8 = Better 0.9 = Very good INDICATORS (Examples) Catch numbers from age group 1 Catch numbers from age group 2 Catch weights from age group 5 Catch weights from age group 4 Proportion of catch numbers Proportion of catch weights CN6 [BAD INDICATOR] r= PATTERNS DONT MATCH CN11 [GOOD INDICATOR] r= PATTERNS MATCH

ESTIMATED INDICATOR Spawning Stock Biomass ESTIMATED INDICATOR Spawning Stock Biomass STOCK INDICATORS (Age based catch numbers and weights) STOCK INDICATORS (Age based catch numbers and weights) TRADITIONAL APPROACH ALTERNATIVE APPROACH COMPARISON FOR WHICH YEARS ? 1. Cod (IS) 2. Megrim (CS & BB) 1. Cod (IS) 2. Megrim (CS & BB) Acceptable In Control Precautionary Limit Out Control

GOODBAD Irish Sea Cod (Gadus morhua) Reference Limits B pa B lim = 10,000t = 5000t CN4 = Catch number from age group 4 CW4 = Catch weight from age group 4 CWABOVE = Catch weight above age group 4 CNABOVE = Catch numbers above age group 4 I – 1970 II – 1978 III – 1990 I – 1970 II – 1978 III – 1990 OC 1995 Traditional Approach - Spawning Stock Biomass CN4 CW4 CWABOVE CNABOVE MATCH COLOUR CODES Traditional Approach - Fishing Mortality

GOODBAD Celtic Sea and Bay of Biscay Megrim (Lepidorhombus whiffiagonis, L. boscii) I – 1990 II – 2004 I – 1990 II – 2004 Traditional Approach - Spawning Stock Biomass CN8 CNPP6 CNPP7 CNPP8 Reference Limits B pa B lim = 55,000t = Not defined CN8 = Catch number from age group 8 CNPP6 = Proportions of catch numbers from age group 6 onwards CNPP7 = Proportions of catch numbers from age group 7 onwards CNPP8 = Proportions of catch numbers from age group 8 onwards Traditional Approach - Fishing Mortality

Pros and Cons Performance of CUSUM was found to be consistent with traditional traffic light approach CUSUM charts as real time monitoring technique for qualitative stock assessments Efficient to detect persistent changes in the system A handy monitoring tool for data limited fisheries Stabilize the catch - Objective Delayed signals occur for quick changes in the system Delayed signals might happen when recruitment to the fishery occurs before maturity