Guidelines for the Collection and In Situ Scientific Study of Stickleback Species Pairs (Gasterosteus spp.)

May 3, 2008

The Recovery Team for Non-Game Freshwater Fish Species in British Columbia:

The following guidelines represent advice from the Recovery Team for Non-game Freshwater Fish Species in British Columbia regarding collection and in situ scientific study of stickleback species pairs. With the exception of a newly-discovered species pair on Nelson Island, British Columbia, stickleback species pairs are listed under the Species at Risk Act (SARA) as endangered. The purpose of the guidelines is to inform regulators issuing collection and study permits under SARA and the BC Wildlife Act. The guidelines are meant to apply to sympatric stickleback species pairs, but the rationale presented may be relevant to other listed fish species in the province. The Recovery Team reserves the right to update the guidelines based on new information or interpretations.

Background

The fish known collectively as “sympatric stickleback species pairs” are small, freshwater fish descended from the marine threespine stickleback (Gasterosteus aculeatus). In each case, one of the species (referred to as "limnetic") primarily exploits plankton, and has morphological traits considered adaptations to a zooplankton-consuming lifestyle. The other species (referred to as "benthic") mainly eats benthic invertebrates in the littoral zone, and has traits considered to be advantageous in benthic feeding. The pattern of morphological and ecological divergence is similar in each of the lakes, such that limnetics all look alike, as do all benthics. Despite similar appearance, phylogenies based on molecular genetics strongly indicate that the pairs are independently derived.

Stickleback species pairs exist in two watersheds on Texada Island, and one on nearby Nelson Island. A pair in Hadley Lake, on Lasqueti Island has been declared extinct, likely due to the introduction of brown bullhead (Ameiurus nebulosus). Another pair in Enos Lake on Vancouver Island has collapsed into a single hybrid swarm, and is unlikely to recover. The present global range is therefore restricted to two watersheds on northern Texada Island - the Paxton Lake watershed, and the Vananda Creek watershed (with three lakes, Balkwill, Priest and Emily) - and Little Quarry Lake on Nelson Island.

Stickleback species pairs have been the focus of intense scientific study since the 1980s and there is an increasing demand for wild stock for use in laboratory-based studies and for permits to conduct in situ scientific study. The Recovery Team has indicated that collecting activities are likely a significant source of mortality on adult fish, and constitute a threat to the species pairs that should be carefully managed.

Recommendations

Collection Locations

The Recovery Team recommends the establishment of no-take areas in each lake to allow reproduction and other ecological processes to proceed undisturbed in portions of each lake. Approximately half of each lake is considered reasonable at this time for this purpose. It is suggested that trapping, seining, and other capture techniques should be prohibited within the no-take areas. This applies to both lethal sampling and capture and release. We acknowledge that occasional captures may be justified for some research programs, but these requests should be reviewed on an individual basis with approval based on merit and risk.

Sampling Quantities and Methods

Scientific collections should constitute less than 10% of the mature fish population, as measured in spring and summer seasons. A mark-recapture studyFootnote 2 assessed abundance in Paxton Lake and indicated approximately 3,300 mature benthic males and 25,800 mature limnetic males. Confidence in the estimate of benthics was considerably greater than that for limnetics. Extrapolated abundance estimates for other species pair lakes based on lake perimeter are summarized in Table 1.

Table 1 describes the estimate of mature benthic Stickleback for each of the species pairs in Paxton Lake, Priest Lake, Balkwill Lake, Emily Lake and Little Quary Lake. The first column lists the names of the lakes where the Stickleback pairs reside. The second column indicates the perimeter (in metres) of Paxton Lake, Priest Lake, Balkwill Lake, Emily Lake and Little Quary Lake. The third column indicates the calculated amount of mature benthic Stickleback pairs in Paxton Lake, Priest Lake, Balkwill Lake, Emily Lake and Little Quary Lake . The fourth and fifth column indicate the lower and upper confidence intervals of the calculated amount of mature benthic Stickleback pairs in Paxton Lake, Priest Lake, Balkwill Lake, Emily Lake and Little Quary Lake.

Table 1. Estimates of mature benthics for each of the species pair lakes. These projected estimates are based on a single mark-recapture estimate of mature benthic males in Paxton Lake in June 2005. All estimates, including 95% confidence intervals, are calculated by multiplying the Paxton Lake estimates by a factor that corrects for lake perimeter, and multiplying by 2 to account for both sexes.
Lake Perimeter (metres) Mature benthic Lower CI Upper CI
Paxton 2277 6,663 4,486 10,610
Priest 3868 11,319 7,620 18,024
Balkwill 2268 6,637 4,468 10,568
Emily 1091 3,193 2,149 5,084
Little Quarry 2700 7,900 5,319 12,581

Lethal sampling

The Recovery Team recommends the following maximum lethal sampling limits. Please note that these are under review and are likely to be updated based on additional information. For example, there is discussion regarding implementing a size restriction for lethal sampling of benthics, to protect large individuals.

Catch and release

In our experience there is some mortality associated with catch and release sampling activities, even where considerable care is exercised. This form of sampling is obviously superior to lethal sampling in terms of direct effects on the population, but some caution is warranted. It is probably reasonable to assume a 5% mortality rate for “non-lethal” sampling, and this should be factored into overall permitting levels. To avoid undue stress on animals, traps should be left in for less than 24 hours. All traps should be accounted for at all times.

Sampling methods

To prevent the spread of invasive species and disease organisms the Recovery Team recommends that all sampling equipment (traps, seines, boats, boots, etc.) be sterilized using appropriate methods prior to moving gear from one lake to another. Treatment with 2% bleach is the most straightforward method at this time, although researchers are encouraged to educate themselves on potential threats and appropriate treatments.

In Situ Scientific Studies - Use of Hybrids

The Recovery Team supports the full prohibition of use of hybrids in experimental studies, where the source of hybrids is not directly from the wild. Hybrids are often reared in laboratory faculties, in experimental ponds, and also occur in Second Lake on Texada Island. Use of hybrids from these sources is considered inappropriate and high risk, whether these individuals are retained in enclosures or not, due to the possibility of escape into the wild. It is acknowledged that such experiments have been conducted in the past, however the Recovery Team has indicated that this is now believed to introduce an unacceptably high risk to wild populations. The primary rationale for this recommendation is that the collapse of the Enos Lake pair and the extinction of the Hadley Lake pair has highlighted the potential fragility of the pairs, and there may be a threshold of hybrid abundance beyond which the species pairs are not able to maintain themselves and would collapse to a hybrid swarm. Note that this recommendation does not preclude the use of wild hybrids from the same lake, or the use of hybrids in laboratory or experimental pond settings.

In Situ Scientific Studies - Transfer of Fish from Other Locations

The Recovery Team supports the full prohibition of transfer of fish from other natural or laboratory locations. Fish are often reared in laboratory facilities and in experimental ponds, and are a potential source of fish for experimental studies. Translocation of fish is considered inappropriate and high risk, whether these individuals are retained in enclosures or not, due to the possibility of escape into the wild and the potential for disease transfer. It is acknowledged that such experiments have been conducted in the past, but the Recovery Team has indicated that this is now believed to introduce an unacceptably high risk to the wild populations.

It should be noted that translocation of fish requires a permit from the BC Ministry of Environment, and all applications will be reviewed by the Transplant Committee.

In Situ Scientific Studies - Use of Non-native Species

The introduction of non-native species is implicated as the primary cause of extinction of the Hadley Lake pair and the collapse of the Enos Lake pair. The Recovery Team recommends full prohibition of use of non-native plant or animal species in experimental studies in the wild. By “non-native species” we refer to all species that do not naturally occur within the watersheds where species pairs occur.