Monitoring Populations in Partially Protected Marine Areas: Comparisons of Length Data Derived from Recreational Angler Surveys and Fishery‐Independent Surveys
In partially protected marine areas, such as recreational fishing havens (RFHs), fishery‐independent surveys and recreational angler surveys represent two of the few available methods of collecting length‐frequency data to monitor population responses to protection from commercial fishing and the impacts of ongoing recreational fishing. Although length data plays an important role in facilitating stock assessment and monitoring within RFHs, little is known about the relative magnitude and direction of size‐selective biases introduced by fishery‐independent surveys and angler surveys. This study quantitatively compared length data derived from the two methods for three exploited species or taxa (bream species complex of Acanthopagrus spp. [hybrid complex of Black Bream A. butcheri × Yellowfin Bream A. australis], Dusky Flathead Platycephalus fuscus, and Sand Whiting Sillago ciliata) sampled from two estuarine RFHs in Australia. When all lengths sampled by each method were compared, the species‐specific length frequencies derived from angler surveys and fishery‐independent surveys differed significantly in all cases but for Dusky Flathead from one RFH. Following standardization for minimum‐legal‐length restrictions, the angler survey method captured a more representative spectrum of lengths for Acanthopagrus spp. For Dusky Flathead, angler surveys and fishery‐independent surveys performed equally in terms of the lengths captured. Although length frequencies for Sand Whiting above minimum legal length differed significantly between the methods in both RFHs, spatial inconsistencies precluded a clear conclusion for this species. The fact that neither method consistently outperformed the other across all species supports the idea that using both angler surveys and fishery‐independent surveys in a complimentary manner may enable a clearer understanding of size compositions across multiple species for monitoring and stock assessment purposes and thereby facilitate an ecosystem‐based approach to fishery assessment and management.