Genetic Analysis of Standardized Collections of Cackling and Canada Goose Harvests

Abstract

Many states have established special harvest seasons and hunting zones to target overabundant populations of temperate‐nesting Canada geese (Branta canadensis) and protect less abundant northern‐nesting populations of Canada geese and cackling geese (B. hutchinsii). To meet management needs for spatially and temporally explicit harvest estimates, we utilized established methods of genetic stock identification and standardized harvest sample collections to estimate proportional contributions of cackling (B. h. hutchinsii) and Canada geese (B. c. maxima and B. c. interior) to 5 consecutive annual harvests (1998‐2002) in Michigan, USA. Harvest samples (n = 2,272) were analyzed for several seasons at statewide, regional, and local spatial scales. We expanded upon previous studies that used genetic methods to monitor cackling goose and Canada goose harvests by analyzing harvests within regional and local goose management areas. Likelihood ratio tests were also employed to compare harvest composition among spatial and temporal sampling groups. Tests revealed that proportions of giant and interior Canada geese within local harvests varied significantly during the fall in different hunt zones of Michigan and during different time periods. Adaptive management of temperate‐nesting and northern‐nesting geese would benefit from accurate estimates of harvest composition, as provided by genetic‐based methods. Quantification of changes in harvest composition as a function of variation in season opening date and duration, and bag limits can provide valuable insight into goose migratory behavior and population dynamics. Harvest composition estimates may be used to predict impacts of management prescriptions on mortality rates of specific breeding populations.

Using 2 Genetic Markers to Discriminate Among Canada Goose Populations in Ohio

“…Our results suggest that 6 microsatellite loci do not allow accurate estimation of interior and giant Canada goose contributions to Ohio harvests and may give erroneous estimates of harvest derivations, despite the fact that previous studies in other geographic areas have successfully accomplished this using a similar set of microsatellite loci , Shorey et al 2007). This discrepancy suggests that a technique developed in one portion of a species' range may not be applicable to other geographic areas, due to genetic differences among populations.…”

“…Though based on only one season and small sample sizes, particularly in the Lake Erie Zone, our results suggest that interior harvest during the regular and late season was slightly higher in the Lake Erie Zone (16.7%) than in the other 2 zones (5% in the North Zone and 10% in the South Zone). Timing of migration and harvest of subarcticnesting populations can vary significantly among years , Shorey et al 2007); therefore, it is important to examine multiple seasons, as well as spatial variation within seasons. Results of an ongoing multi-year study will better elucidate the spatial and temporal variation in the composition of Ohio's Canada goose harvest.…”

“…An understanding of the spatial and temporal variation in harvest composition is necessary to identify the appropriate management options to accomplish these goals. Genetic techniques provide a viable alternative to traditional methods of estimating harvest derivations, such as band recovery analyses and morphometric discrimination , Shorey et al 2007. Both individual-level and population-level genetic methods have potential for estimating harvest composition.…”

“…At the population level, mixed stock analysis (MSA; Pella and Milner 1987) uses allele frequencies in all potential contributing (baseline) populations and maximum likelihood methods to estimate proportional contributions of each population or subspecies to admixed harvest samples. In Michigan and the Pacific Northwest, MSA has been successful in estimating proportional contributions of Canada goose and cackling goose (Branta hutchinsii) subspecies and management populations Inman et al 2003;Scribner et al 2003Scribner et al , 2005Shorey et al 2007), but these methods have not been rigorously tested in widespread geographic areas, despite potential applicability throughout North America and across all 4 flyways. Most previous studies employing MSA have employed biparentally inherited, nuclear microsatellite loci , Shorey et al 2007), but maternally inherited mitochondrial DNA (mtDNA) variation has also shown sufficient discriminatory power in some applications .…”

Discrimination among similarly colored goose species in federal harvest surveys

“…Managers have expressed concern that the body size of some species may have changed during this time, particularly for Ross's geese and the midcontinent population of lesser snow geese (A. c. caerulescens), in which there is evidence of recent population declines and effects of density dependence (Alisauskas et al 2022, Baldwin et al 2022, Weegman et al 2022. Lastly, Wingbee species' discrimination thresholds were based only on morphological analyses, whereas genetic-based approaches may provide more accurate discrimination (Inman et al 2003, Shorey et al 2007.…”