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Keywords: conservation planning; dolphins; fisheries bycatch; PBR; population viability analysis; potential biological removal; PVA; SAMSE; análisis de viabilidad; AVP; captura incidental pesquera; delfines; EBP; extirpación biológica potencial; MASAM; planeación de la conservación; , , , (Potential Biological Removal; PBR), (PVA), (SAMSE) EN conservation planning dolphins fisheries bycatch PBR population viability analysis potential biological removal PVA SAMSE análisis de viabilidad AVP captura incidental pesquera delfines EBP extirpación biológica potencial MASAM planeación de la conservación , , , (Potential Biological Removal PBR), (PVA), (SAMSE) 1 12 12 08/01/22 20220801 NES 220801 INTRODUCTION Mortality caused by incidental capture, or bycatch, in commercial fisheries is an ongoing, global problem for conservation and sustainable fisheries management (Read et al., 2006). For bycatch 3, we used dolphin capture rates of 50 per year, as reported by independent observers in 2002 (Stephenson & Chidlow 2003) and similar to observer-reported rates from 2006 to 2009 (Allen et al., 2014), or a 3-year capture rate of 150 dolphins. We also set up 1 max bycatch scenario based on a hypothetical maximum catch rate derived from the statement by the then Western Australian Department of Fisheries (DoF) that the "number of dolphins caught by the fishery should be <75/year, assuming 100% catch mortality" (Fletcher & Santoro 2010, p. 313) (3-year capture rate 225 dolphins). Thus, we adjusted calf, juvenile, and adult mortalities by adding the respective number of bycatch mortalities to the number of mortalities of the baseline scenarios (Appendix S3). [Extracted from the article]

The forecast for the viability of populations depends upon metapopulation dynamics: the combination of reproduction and mortality within populations, as well as dispersal between populations. This study focuses on an Indo‐Pacific bottlenose dolphin (Tursiops aduncus) population in coastal waters near Bunbury, Western Australia. Demographic modeling of this population suggested that recent reproductive output was not sufficient to offset mortality. Migrants from adjacent populations might make up this deficit, so that Bunbury would act as a "sink," or net recipient population. We investigated historical dispersal in and out of Bunbury, using microsatellites and mitochondrial DNA of 193 dolphins across five study locations along the southwestern Australian coastline. Our results indicated limited gene flow between Bunbury and adjacent populations. The data also revealed a net‐dispersal from Bunbury to neighboring populations, with microsatellites showing that more than twice as many individuals per generation dispersed out of Bunbury than into Bunbury. Therefore, in historic times, Bunbury appears to have acted as a source population, supporting nearby populations. In combination with the prior finding that Bunbury is currently not producing surplus offspring to support adjacent populations, this potential reversal of source‐sink dynamics may have serious conservation implications for Bunbury and other populations nearby. [ABSTRACT FROM AUTHOR]

Genetic diversity is essential for populations to adapt to changing environments. Measures of genetic diversity are often based on selectively neutral markers, such as microsatellites. Genetic diversity to guide conservation management, however, is better reflected by adaptive markers, including genes of the major histocompatibility complex (MHC). Our aim was to assess MHC and neutral genetic diversity in two contrasting bottlenose dolphin (Tursiops aduncus) populations in Western Australia—one apparently viable population with high reproductive output (Shark Bay) and one with lower reproductive output that was forecast to decline (Bunbury). We assessed genetic variation in the two populations by sequencing the MHC class II DQB, which encompasses the functionally important peptide binding regions (PBR). Neutral genetic diversity was assessed by genotyping twenty‐three microsatellite loci. We confirmed that MHC is an adaptive marker in both populations. Overall, the Shark Bay population exhibited greater MHC diversity than the Bunbury population—for example, it displayed greater MHC nucleotide diversity. In contrast, the difference in microsatellite diversity between the two populations was comparatively low. Our findings are consistent with the hypothesis that viable populations typically display greater genetic diversity than less viable populations. The results also suggest that MHC variation is more closely associated with population viability than neutral genetic variation. Although the inferences from our findings are limited, because we only compared two populations, our results add to a growing number of studies that highlight the usefulness of MHC as a potentially suitable genetic marker for animal conservation. The Shark Bay population, which carries greater adaptive genetic diversity than the Bunbury population, is thus likely more robust to natural or human‐induced changes to the coastal ecosystem it inhabits. [ABSTRACT FROM AUTHOR]