Information for identification of candidate critical habitat of Little Quarry Lake benthic and limnetic threespine sticklebacks (Gasterosteus aculeatus)

Abstract

Little Quarry Lake Benthic and Limnetic Threespine Sticklebacks (Gasterosteus aculeatus) are endemic to Little Quarry Lake on Nelson Island, British Columbia (BC). This benthic-limnetic species pair is one of three known extant and genetically distinct pairs found in BC. The benthic and limnetic forms differ genetically and in body morphology, habitat use, and feeding ecology (McPhail 1984; Ridgway and McPhail 1984; Bentzen and McPhail 1984; Bentzen et al. 1984). The pair are kept genetically distinct by low levels of hybridization attributed to a combination of morphological, behavioural, and ecological differences (Bentzen et al. 1984; Ridgway and McPhail 1984; Gow et al. 2008). The major potential threat to the two species is the introduction of invasive species, which can alter the habitat in such a way that could dissolve reproductive barriers and the ability of these two fish species to recognize mates, resulting in increased hybridization (cf. Taylor and Piercey 2018). In 2015, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assessed both Little Quarry Lake Benthic and Limnetic Threespine Sticklebacks as Threatened. The species are under consideration for listing under Schedule 1 of the Species at Risk Act (SARA; 2002). If listed, critical habitat (CH) must be identified as a part of the recovery strategy. Critical habitat is defined in the Species at Risk Act as “…the habitat that is necessary for the survival or recovery of a listed wildlife species and that is identified as the species’ critical habitat in a recovery strategy or in an action plan for the species” [s. 2(1)]. Under SARA S.41.1(c) a species’ critical habitat must be identified “to the greatest extent possible, based on the best available information, including the information provided by COSEWIC, and examples of activities that are likely to result in its destruction.” Fisheries and Ocean Canada (DFO) Species at Risk Program has requested science advice in support of the identification of candidate critical habitat necessary for the survival or recovery of Little Quarry Lake Benthic and Limnetic Threespine Sticklebacks, which will be used to inform the identification of critical habitat under SARA. The specific objectives of this review are to: Objective 1: Review information available on the habitat necessary for survival and recovery of Little Quarry Lake Benthic and Limnetic Threespine Sticklebacks and identify the function, features, and attributes of this habitat across life stages. Objective 2: Present candidate critical habitat spatial attributes. This Science Response Report results from the May 30, 2023 regional peer review on the Information for identification of candidate critical habitat of Little Quarry Lake Benthic and Limnetic Threespine Sticklebacks (Gasterosteus aculeatus).