Proceedings of the 2007 Georgia Basin Puget Sound Research Conference
Session 4B: Northern Abalone Recovery
Chair: Don Rothaus
Changes in Abundance and Size of Pinto Abalone (Haliotis kamtschatkana) in the San Juan Archipelago (1979 to 2006)
Pinto abalone (Haliotis kamtschatkana) populations in the San Juan Archipelago (SJA) have been monitored periodically by the Washington Department of Fish and Wildlife from 1979 through 2006. Alarming decadal changes in abundance and size frequency have been documented. A comparison between timed twenty minute dive surveys at 23 sites showed a roughly 50 % decrease in abalone from 1979 to 1991. In 1992 a new methodology was adopted using ten permanent index stations located throughout the SJA. These have been re-surveyed in 1994, 1996, 2003, 2004, 2005 and 2006. A decrease in total abundance occurred from 1992 to 1994 (n=351 to n=288). The fishery was closed shortly after the 1994 survey based on the continued declining trend. From 1992 to 2006 there has been a 77% reduction in abalone abundance at these index stations. A significant 10 mm right shift in mean size of abalone occurred during this same time period. Linear regression of abundance data predicts that these 10 sites will be extirpated by 2010. Literature suggests that sedentary invertebrates, such as abalone, must be at densities > 0.33-0.15 abalone/m2 for successful fertilization. Currently, all index stations have densities well below 0.15 abalone/m2. Abalone < 90 mm represent < 4 % of the individuals encountered in 2006. These data are indicative of “Allee Effect” response to low population densities. Both WDFW (in 1996) and NOAA Fisheries (in 2004) have listed pinto abalone as a “Species of Concern”.
Northern Abalone and Engineering Species in the San Juan Islands: Implications for Restoration Strategies
Northern abalone, Haliotis kamtschatkana, once common on subtidal rocky reefs may now be scarce in the San Juan Islands and throughout the Pacific Northwest. We compared the abundance of northern abalone today with data from 25 years ago in the San Juan Islands and northern California. In the San Juan Islands, we examined which habitat engineers were associated with the presence of adult northern abalone. Our results show that northern abalone have declined to critically low levels in the San Juan Islands and in northern California. Furthermore, no juvenile or small northern abalone (<75mm) were observed at any of the sites. Adult northern abalone were significantly more abundant at sites with kelp beds (X2=18.8, d.f.=2, p=0.01) compared with sites with sea urchin spine canopy. Abalone abundance was correlated with other mollusks including rock scallops and white cap limpets (R2=0.542, F= 9.52, p=0.01). Reserve status of the site was a poor predictor of adult northern abalone and rock scallop abundance. The combination of no juvenile abalone coupled with low abundances of adults is indicative of recruitment failure and the need for aggressive conservation actions. Determining critical habitat features and associated species can guide future site selection for management and restoration efforts.
Early Life History Dynamics of the Pinto Abalone (Haliotis Kamtschatkana) in the San Juan Archipelago, Washington State
Pinto abalone (Haliotis kamtschatkana) are in serious decline in Washington state, possibly due in part to Allee effects and recruitment failure. Sixty-six abalone recruitment modules (ARMs) deployed at three sites in the San Juan archipelago (SJI) and surveyed in situ six times over 26 months attracted only three juvenile abalone. Declines could also be attributed in the northern SJIs to elevated temperatures and lowered salinities observed from the Fraser River summer plume. To test this hypothesis, a 3x3 full factorial experiment was implemented to examine the influence of environmentally relevant temperature and salinity combinations on post-larval survival. By day three 100% mortality was observed in all 14psu treatment groups regardless of temperature. Mortalities in each of the remaining temperature/salinity combinations over the 14 day study were not significant. Based on these results, single-factor experiments were conducted in which post-larvae, veliger larvae, and trochophore larvae were challenged with a range of treatment salinities (14-32psu). 100% mortality was observed in all post-larval treatments below 23psu. Over 98% mortality of trochophore larvae was observed when exposed to salinities below 26psu, while larvae challenged as day three veligers showed greater tolerance of salinities between 23-26psu. These studies suggest early intolerance to salinities at or below 23psu, conditions that are often observed in the northern SJIs during summer months.
Evidence for a Cryptic Form of Abalone in Washington State, and Impact on the Census Size of Populations of Pinto Abalone in the Region
In Washington State, where fishery closures in the 1990s have failed to prevent the decline of pinto abalone, genetic analysis of the population structure of the species has direct relevance to its conservation. We extended the northern and southern ranges of a previous genetic survey, and detected minor differentiation between pinto populations. However, we noted that populations from the interior coasts (northern Puget Sound, Washington and Ketchikan, Alaska) were significantly different from those on the outer coast (British Columbia and Sitka, Alaska). Population assignment methods discriminated a group of divergent individuals aggregated around South Long Island in northern Puget Sound. These individuals were morphologically indistinguishable from pinto abalone, and also occurred at lower frequency in samples throughout the species range. We further clarified the taxonomy of this newly identified form using maternally inherited mitochondrial DNA and reproductive proteins, and derived a full census of both forms of abalone in the region. To date, our results indicate that this form may be flat abalone, but the full range of phenotypic diversity and distribution in this species has not been previously recognized. Our findings have significant impact accuracy of population counts of pinto abalone, and highlight the reduced potential for recovery in this species.
Three Approaches to Out-Planting Hatchery-Reared Pinto Abalone (Haliotis kamtschatkana) British Columbia, Canada.
The Bamfield Huu-ay-aht Community Abalone Project has been conducting research on the out-planting of pinto abalone (Haliotis kamtschatkana) in Barkley Sound, B.C. Canada. BHCAP has taken a 3-pronged approach to out-planting young abalone: 1. larvae 2. 1-2 month-old juveniles, and 3. 1 year-old juveniles. Wild broodstock are collected from the field and conditioned for spawning in the hatchery. Larvae generated are raised for their 2-week planktonic phase and when competent for settlement, are either out-planted or set in the hatchery. There are practical and biological advantages to out-planting very young animals. For larval out-planting, larval development is monitored and anatomical and behavioural characteristics indicate when they are approaching competence to settle. The larvae are counted and packaged for transport (up to 24 hours by land, sea or air). At the out-planting site, larvae are treated with GABA to trigger settlement, then put into wide-bore syringes with a dye marker, taken underwater by divers and released into crevices and spaces between rocks. Out-planting of 1-2 month old juveniles is done by settlement of the larvae onto concrete blocks contained in modules, in the hatchery. The modules are held for 1-2 months in the hatchery until the juveniles reach approximately 1 mm shell length. They are then transferred in totes of seawater, loaded onto the dive boat and placed on the sea bed by divers. The use of modules protects the fragile juveniles from handling damage, provides a refuge from predators for them in the field and increases the chance that out-plants will remain in the same location. Year-old juveniles were out-planted prior to their conversion to a kelp diet (prior to a subsequent change in shell colour in the hatchery). The juveniles are removed from hatchery plates, packaged for transport and placed on cleanly brushed substrate by divers. Since November 2003, BHCAP has out-planted 4 million larvae, 150,000 1-2 month old juveniles and 2000 year-old juveniles (8 mm mean shell length) at 3 sites. Baseline population surveys were conducted prior to out-planting and follow-up surveys will soon be completed to determine the success of the project.in British
Wild Brood-Stock Aggregations as a Recovery Tool for the Northern Abalone (Haliotis Kamtschatkana) in the Pacific Rim National Park Reserve of Canada, British Columbia.
One of the five key objectives of the National Recovery Strategy for the Northern abalone (Haliotis kamtschatkana) in British Columbia is to conduct research on rebuilding methods. The strategy prioritizes studies to assess the efficacy of wild abalone transplant aggregations (i.e., brood-stock aggregations) to enhance local spawning success and reproductive output. Abalone recruitment was studied at eight locations (each with two replicate stations) within the Broken Group Islands along a modeled current pathway in the fall of 2004 and the winter of 2005. The results suggest that wild brood-stock aggregations may be an effective rebuilding technique for Northern abalone. We found a significant inverse relationship (r2 = 0.86; P < 0.001) between recruit [i.e., shell length £ 30 mm] density and distance (km) from the brood-stock aggregation. A significant positive relationship (r2 = 0.63; P < 0.02) was also detected between recruit densities and the relative index of exposure. Potential effects of various habitat characteristics (e.g., abundance of competitors, predators, substrate type, etc.) are discussed. These results provide strong evidence for a downstream dispersion gradient of juvenile Northern abalone from a wild brood stock aggregation, and suggest that wild brood-stock aggregations may be a viable and cost effective rebuilding tool.
Federal Protection for Northern Abalone in the USA: Comparing and Contrasting the Process and Potential Outcomes of Species of Concern Versus ESA Listings
In 2004, the National Marine Fisheries Service (NMFS) established a Species of Concern (SOC) list for species about which NMFS has concerns regarding status and threats, but for which insufficient information is available to indicate a need to list under the Endangered Species Act (ESA). NMFS added northern abalone to the SOC list to promote research and proactive conservation efforts and potentially negate the need for ESA listing. Progress has been made to identify data deficiencies, stimulate cooperative research efforts, and foster voluntary efforts for providing stewardship. The scope of the SOC program is constrained, however, by limited funding opportunities and NMFS’s inability to regulate activities that pose threats. If evidence suggests that an ESA listing is warranted, NMFS may consider initiating the listing process for a species. This process involves compiling the best available data, determining what constitutes a species, assessing extinction risk, and evaluating conservation efforts underway to determine if they mitigate extinction risk such that listing is not warranted. The goal of an ESA listing is to conserve and protect at risk species by prohibiting take and by ensuring that federal agencies do not jeopardize the continued existence of the species or adversely modify their habitat.
Developing a Sound Recovery Strategy for the First Endangered Marine Invertebrate, White Abalone (Haliotis Sorenseni)
White abalone, a deeper-water species inhabiting kelp forest habitats of the southern California and central Baja California coasts, became the first marine invertebrate to be added to the Endangered Species List in May 2001. Critical to developing a recovery plan for white abalone is better understanding the factors that led to its decline, improving estimates of abundance, gaining a better understanding of the species’ life history, and refining the focus of future conservation efforts. A threats assessment revealed that the impact of fishery exploitation was likely the major cause for the species’ decline. Recent surveys revealed that the total population size in the US may be higher than previously estimated because the amount of suitable habitat identified at these sites (3, 646 ha) is more than 10 times greater than previously estimated (202 ha). However, densities remain at least an order of magnitude lower (3-50 per ha) than pre-exploitation densities (479-2,300 per ha). Future recovery activities should focus on determining the critical densities required for successful spawning, the spatial scale over which recruitment dynamics are operating, and whether artificial enhancement may help in achieving the critical, scale-specific densities necessary for recovery and long-term viability of the species.