Testing translocation as a recovery tool for pink (Haliotis corrugata) and green (Haliotis fulgens) abalone in Southern California.
KEY WORDS: abalone, aggregation, Allee effects, conservation, enhancement, restoration, Haliotis corrugata, Haliotis fulgens
Pink (Haliotis corrugata) and green (Haliotis fulgens) abalone were once abundant in southern California, supporting vital commercial and recreational fisheries until stock declines resulted in fishery closures in 1995. Southern California abalone landings once exceeded 2000 mt/y during the 1950s and 1960s, but rapidly declined in the 1970s and 1980s (Karpov et al. 2000). During the peak decade of the fishery for pink abalone (1950 to 1959), more than 9.3 million abalone (12,328 mt) were fished (Rogers-Bennett et al. 2002). Green abalone were less important in the fishery such that, during the peak decade from 1966 to 1975, approximately 1.5 million abalone (1,137 mt) were fished (Rogers-Bennett et al. 2002). The top-producing location in the historic fishery for both pink abalone and green abalone was San Clemente Island and, to a lesser extent, Santa Catalina Island. Withering foot syndrome, a chronic wasting disease of abalone (Friedman et al. 2000), may have contributed further to the decline in the stocks from the mid 1980s until the closure, probably affecting pink abalone more than green (Moore et al. 2009). However, at the time of the onslaught of the disease, both species stocks were very low and were virtually nonexistent in commercial fishery landings (Karpov et al. 2000). Pink and green abalone are now estimated to be at less than 1%of their baseline densities based on historic landings (Rogers-Bennett et al. 2002).
The major threats to pink and green abalone populations today are low densities and the possibility of reduced reproduction resulting from Allee effects (Allee 1931). Low densities of broadcast spawners such as abalone can lead to poor fertilization success as distances between males and females increase (Babcock & Keesing 1999), leading to recruitment failure. Recruitment from distant populations may be limited, as suggested by data from drift tube studies (Tegner & Butler 1985). Moreover, the planktonic period is short (<1 wk) for abalone species in southern California (Leighton 1974) and recruitment of pink and green abalone juveniles has been poor inside small abalone modules in the northern Channel Islands (Rogers-Bennett et al. 2004). Given the depressed population size of local densities, nearest neighbors may be too far apart to reproduce successfully. Pink abalone in San Diego, California--where densities exceed most other sites in southern California--were low (0.017 abalone/[m.sup.2]), corresponding to a nearest neighbor distance greater than 5 m (Catton & Rogers-Bennett 2013). Today, populations are comprised primarily of solitary abalone, many of which may not be contributing to reproduction.
Translocation has been recommended as a promising tool for pink and green abalone restoration, as a means to enhance local densities and potentially boosting fertilization and reproduction success. Translocation may be superior to captive rearing and stocking strategies (Tegner 1992, Kanamaru et al. 1993, Tachiyama & Futashima 1993, Heasman et al. 2004), especially in cases when stocking recapture rates are poor. Despite massive seeding investments in Japan, wild stocks have not increased dramatically; however, the fishery does continue to fish stocked abalone (Seki & Sano 1998).
Translocation was used as early as 1929 by the Japanese to enhance the growth rates of abalone on fishing grounds, and results showed increased local reproduction (Saito 1979). Abalone translocation using wild stock has occurred using a variety of abalone species, with a few studies conducted in southern California. Henderson et al. (1988) transplanted 517 pink abalone and recorded 18% mortality with a loss of 78% of the remaining abalone, suggesting illegal take might have contributed to some of the losses. Similarly, Tegner (1992) transplanted 4,453 green abalone with approximately 10% recaptures 1.5 y later, and there, too, was suspicion that illegal fishing may have played a role in the results. These studies recommended future translocation work to focus on enforcement, minimization of handling stress, and maximization of bottom preparation prior to transplantation. Substrate preparation may be a crucial factor contributing to an increase in persistence and survival of translocated animals in restoration sites.
In the current study, a pilot translocation experiment was initiated to test the effectiveness of this method for maintaining spawning aggregations at San Clemente and Santa Catalina islands, which once had healthy populations of both pink and green abalone. Abalone were tagged and translocated into aggregation sites or tagged at control sites and monitored for approximately 1 y. We discuss the implications of species-specific movement behavior as it relates to the usefulness of translocation as a strategy to bolster local densities for reproduction and restoration.
Translocation experiments were conducted at San Clemente Island for pink abalone and Santa Catalina Island for green abalone (Fig. 1). San Clemente Island is located approximately 120 km northwest of San Diego, California, and is 39 km long and 6.5 km at the widest point. Pink abalone sites were established at Seal Cove (SC), West Cove (WC), and Fish Hook (FH). Santa Catalina Island is located approximately 35 km south-southwest of Los Angeles, California, and is 35 km long and 13 km wide. Green abalone sites were located at Arrow Point (AP), Chalk Cove (CC), and at Blue Caverns (BC). Four sites were chosen for each island, including 2 treatment (translocation) and 2 control sites. Site selection included historically important sites with current remnant abalone populations as well as criteria that included preexistence of abalone aggregations within site boundaries, available food resources, and suitable substrate.
Translocation and control sites between the islands differed in size, depth, and habitat composition based on species preference. Pink abalone sites were in deeper water (8-15 m) with a high percentage of reef structure and more high relief than the green abalone sites. Green abalone sites were comprised of tidally influenced shallow water (2-6 m) with mostly low and medium relief, including complex reef and boulder habitats dominated by cracks, crevices, and ledges. The percentage of algal cover was high for each site at both islands and consisted of mostly giant kelp (Macrocystis pyrifera), Laminaria farlowii, and Eisenia arborea for pink abalone sites; and surfgrass (Phyllospadix sp.), giant kelp (M. pyrifera), Egregia menzesii, and Sargassum fillicinum for green abalone sites.
The size of the sites for the pink and green abalone differed in terms of the availability of abalone at each island. The less abundant pink abalone were placed in 5 x 5 m (25 [m.sup.2]) sites divided into 4 quadrants of equal proportions; the more abundant green abalone were placed in sites measuring 10 x 10 m (100 [m.sup.2]) and were also divided into 4 equal quadrants. Anchored stainless steel eyebolts were affixed to the reef, marking the corners, sides, and center of the site; and
a lead line was attached to the bolts outlining the borders.
Translocation sites were prepared to create artificial abalone scars, and all predator and competitor species were removed. Compressed air-operated chisels and grinders were used to modify the substrate, removing epiphytic and encrusting organisms, revealing the smooth bedrock to simulate a natural abalone scar. Divers prepared the bottom only within the site boundaries to create more artificial scars than the total number of transported abalone to the site. The high number of foot scars would allow abalone to reposition within the site after initial placement. Further site preparation included the removal of sea urchins including purple sea urchins (Strongylocentrotus purpuratus), red sea urchins (Strongylocentrotus franciscanus), black sea urchins (Centrostephanus coronatus), and giant-spine sea stars (Pisaster giganteus).
Translocation and Tagging
Adult-size abalone used for translocation were collected from nearby areas not exceeding 0.5 km from each monitoring site. Abalone removal was done carefully to prevent injury. Solitary abalone were targeted; larger aggregations were left alone. All abalone were brought aboard the boat and kept in a live-well prior to tagging.
Abalone were assessed visually to document potential causes for tag loss or mortality. Shell length was measured (to the nearest millimeter) and animals were evaluated for cuts or abrasions to the foot or epipodium, shell chips, and presence of boring sponges. Cuts or abrasions were recorded as light (<0.6 cm), medium (>0.6 cm to <1.3 cm), or heavy (>1.3 cm). Shell chips to the anterior, posterior, and lateral edges of the shell were recorded. Boring sponge infestation was recorded as light, moderate, or heavy. Preexisting abalone at the translocation site were observed for shell damage only and were measured. Assessments were used to eliminate unhealthy abalone from the study or to explain mortalities during the removal process.
The tagging procedures for translocated and preexisting abalone were similar except that preexisting abalone were tagged in situ. Each abalone received a PIT tag (Biomark 134.2 kHz; length, 12.45 mm) and a disc tag (Series A-16, 304 stainless steel with a 1.9-cm diameter and an 0.8-cm thickness with stamped unique numbers; Short Order Products, Hacienda Heights, CA). Prior to tag placement, the shell was scrubbed with a steel wire brush to remove epiphytes, barnacles, encrusting worms, and so forth. A 2-part marine epoxy (Z-SPAR Splash Zone) was used to place the 2 types of tags on the shell. The PIT tag was placed inside a small amount of the epoxy (diameter, approximately 3 cm) atop the shell on the opposite side of the respiratory pores. The epoxy was flattened and smoothed out, conforming to the shape of the shell. The disc tag was applied directly into the middle of the epoxy and pushed down until secured (depth, approximately 3-5 mm). For translocated abalone, the epoxy was left to set for 20-30 min prior to divers replacing the abalone at the site. Great care was taken to minimize the amount of time abalone remained out of water, and abalone were placed in a live-well during the epoxy set period. Abalone were placed atop a plastic tub lid lined with mesh net for ease of replacing the animals onto the reef.
Abalone monitoring was conducted after initial tagging as well as over time to determine their survival, persistence at the site, and movement outside of the sites. Translocation sites were visited more frequently than control sites. For green abalone at Santa Catalina Island, monitoring at translocation sites started 24 h after tagging and continued the first 2 wk of the first month. Subsequent long-term monitoring occurred once every 3-6 mo until the end of the study. San Clemente Island sites were visited only 2-6 times/y because of the remoteness of the island, inclement weather, and regular U.S. Navy military closures.
Scuba divers surveyed 1 quadrant at a time, dividing the work between 1 or 2 buddy teams to ensure that sufficient time was allotted to find all possible abalone at the site. Primarily, individual abalone were observed by visually reading the external-disc tag. If the disc tag was unreadable or the abalone was in a crack, ledge, or hole, the use of an underwater PIT reader was necessary to confirm the tag number; otherwise, the abalone was noted as having a "no read" tag when the tag or epoxy was observed but could not be read. Immigrant abalone that were not tagged were also enumerated and measured. Notes on tag damage or absence were recorded.
In addition to site monitoring, divers swam a 10-m perimeter of the site boundaries to search for emigrated abalone and mortalities. When time permitted, divers swam beyond 10 m. Abalone distance was measured to the nearest boundary corner and a compass heading was taken providing information on abalone location.
In total, 48 pink abalone were tagged at San Clemente Island translocation sites, including 35 translocated and 13 preexisting (Table 1). At the SC translocation site, 3 of the 8 preexisting abalone (38%) and 18 of the 20 (90%) translocated abalone remained in the site 391 days after translocation. One dead abalone was found at SC 1 day after tagging and was not used in this calculation. Site density at the SC translocation site increased from 0.28 abalone/[m.sup.2] prior to translocation to 1.12 abalone/[m.sup.2] after translocation and ended at 0.92 abalone/[m.sup.2], which is an overall site increase of 70%. The density of the preexisting abalone decreased by 57%, from 0.28 abalone/[m.sup.2] to 0.12 abalone/[m.sup.2], and density for translocated abalone decreased by 14%, from 0.84 abalone/[m.sup.2] to 0.72 abalone/[m.sup.2] (Fig. 2). No-read tags comprised 3 7% of the tags at the site. One abalone immigrated into the site during the late stages of the study, but was neither tagged nor included in our results. The density of translocated abalone declined slightly after translocation until day 349, but then increased on day 391 (Fig. 2).
At the FH translocation site, 3 of the 5 (60%) preexisting abalone and 11 of the 14 (79%) translocated abalone remained in the site 133 days after translocation. There were no observed mortalities at this site, but 1 preexisting abalone was unaccounted for 1 day after tagging. Throughout the course of the study, the preexisting abalone density at this site did not change; however, the density did fluctuate, with a decline prior to translocation (0.08 abalone/[m.sup.2]) and then increases at later dates. Density prior to translocation was 0.12 abalone/[m.sup.2] and increased 86% to 0.56 abalone/[m.sup.2] by the end of the study; however, density for translocated abalone decreased 21%, from 0.56 abalone/[m.sup.2] to 0.44 abalone/[m.sup.2] (Table 1). Density for preexisting abalone at FH after translocation remained unchanged, including 1 missing and 1 added abalone. Density for translocated abalone remained stable until it decreased slightly 85 days after translocation (Fig. 2).
The number of tagged control abalone at the control sites at WC was 4 and at SC was 3 (Table 2), which was much lower than tagged pink abalone at the translocation sites. Two of the control abalone at WC were not found by the end of the monitoring duration of 826 days. Two of the 3 control abalone from SC were found after 825 days. Density decreased from 0.16 abalone/[m.sup.2] to 0.08 abalone/[m.sup.2] at WC control, and from 0.12 abalone/[m.sup.2] to 0.08 abalone/[m.sup.2] at SC control.
In total, 139 green abalone were tagged at the Santa Catalina Island translocation sites, including 113 translocated and 26 preexisting. At the CC translocation site, 2 of the 12 (17%) preexisting abalone and 8 of the 50 (16%) translocated abalone remained in the site 405 days after translocation. One known abalone mortality was observed at the CC translocation site 10 days after it was tagged and was not used in this calculation. Density for preexisting abalone decreased by 83%, from 0.12 abalone/[m.sup.2] to 0.02 abalone/[m.sup.2], and density for translocated abalone decreased by 84%, from 0.51 abalone/[m.sup.2] to 0.08 abalone/[m.sup.2] (Table 3). Prior to translocation, the density at the CC translocation site was 0.12 abalone/[m.sup.2], and on day 405 was 0.11 abalone/[m.sup.2]. No-read tags comprised 2-30% of the total abalone tagged, and after 1 day, no-read tags totaled 19 of the 46 abalone found in the site. As monitoring went on, no-read tags became uncommon and accounted only for 1 abalone on the last day of the survey. Densities for preexisting and translocated abalone decreased dramatically throughout the monitoring duration (Fig. 3). After 14 days, translocated abalone density decreased 84%, from 0.51 abalone/[m.sup.2] to 0.08 abalone/[m.sup.2].
At the AP translocation site, 2 of the 14 (14%) preexisting abalone and 1 of the 58 (2%) translocated abalone remained in the site 388 days after translocation. Four abalone mortalities were observed 1 day after translocation and were not used in this calculation. Density for the preexisting abalone decreased 86%, from 0.14 abalone/[m.sup.2] to 0.02 abalone/[m.sup.2], and density for translocated abalone decreased 98%, from 0.62 abalone/[m.sup.2] to 0.01 abalone/[m.sup.2] (Table 3). Prior to translocation, the density in the site was 0.14 abalone/[m.sup.2]; 388 days after translocation, the density was 0.11 abalone/[m.sup.2]. No-read tagged abalone comprised of 9-29% of the total abalone tagged, and peaked at 22 no-read tagged abalone 21 days after translocation. The density of translocated abalone decreased by 63% 1 day after tagging and stabilized at near 0.20 until day 14 (Fig. 3). Subsequently, very few translocated and preexisting tagged abalone remained in the site.
In total, 6 of the 47 (13%) abalone tagged at the BC control site remained after 931 days (Table 4). Immigrant abalone counts changed constantly and maxed out at 1.69 abalone/[m.sup.2] during the first visit after tagging; immigrant counts subsequently decreased 76% after 119 more days. At the AP control site, 7 of the 16 (44%) tagged abalone were found after almost 2 y, which is a higher rate than at BC control site. At the AP control site, immigration numbers changed constantly and ranged from 0.27-0.95 abalone/[m.sup.2] for 3 visits.
Outside site perimeter searches resulted in 9 and 11 tagged abalone for the CC and AP translocation sites, respectively, which equates to 14% of the total tagged abalone leaving the site boundaries at each site. Abalone resightings occurred 6 times at each site. At the CC translocation site, translocated abalone made up 78% of the total found; at the AP translocation site, translocated abalone comprised of 82% of the total found.
The overall density with tagged and immigrant abalone combined at the translocation sites ranged from 0.22-0.60 abalone/[m.sup.2] for the CC translocation site and 0.21-0.88 abalone/[m.sup.2] for AP translocation site (Table 5). Immigrant density was in constant flux for both sites, and consistently made up a high proportion of abalone within both translocation sites at CC and AP.
Translocation as a Restoration Strategy
Results from our pilot translocation restoration project suggest that translocation may be a promising restoration tool for pink abalone, but not green, because of differences in movement behavior. At one site, pink abalone aggregations remained at high densities (>0.7 abalone/[m.sup.2]) and were stable for more than 1 y. In contrast, green abalone aggregations declined rapidly, from 0.5 abalone/[m.sup.2] to less than 0.1 abalone/[m.sup.2]. Pink abalone were more sedentary whereas the green abalone moved whether they were translocated or were preexisting at the site. In addition, we documented considerable immigration of other green abalone into the study sites throughout the study period. The high rate of movement is demonstrated by several tagged individuals that were found from 60-300 m from our sites during the study. Abalone have been known to move considerable distances (Shepherd 1986, Ault & DeMartini 1987, Tegner & Butler 1989), which can make restocking projects challenging and ineffective, and therefore suggests that translocation may not be an appropriate recovery tool for green abalone.
The results of this study contrast with past translocation studies for pink abalone. Henderson et al. (1988) reported only a 22% persistence rate for pink abalone 1 y after translocation of animals moved from San Clemente Island to Santa Catalina Island during the early 1980s. In the current study, we demonstrated greater persistence rates for pink abalone, from 79% at 1 site after 4 too, and up to 90% at our other site 1 y after translocation. The high rate of persistence over a long period of time could improve reproductive success and increase larval output in the local area, thus enhancing recovery of the species. Key factors that may have led to the high rate or persistence after translocation in our study versus that of Henderson et al. (1988) was the preparation of substrate, predator and competitor control (Tegner & Butler 1989), and a different tagging method, which may have been less invasive. We found that green abalone were more cryptic whereas pink abalone were found in more open habitats. The use of the underwater PIT reader facilitated the relocation of cryptic abalone in the study sites. An observed tag loss rate of only 4% for pink abalone and 1% for green abalone further demonstrated our ability to track our pilot abalone.
In a similar abalone tagging study done in the laboratory using pinto abalone (Haliotis kamtschatkana kamtschatkana), Hale et al. (2012) reported external tag retention of 80% and survival of 90% over a 15-mo period. Our study used similar tagging methods on wild abalone and appears to corroborate the high tag retention and survival results of Hale et al. (2012). This tagging methodology enabled us to test effectively the feasibility of translocation for population restoration over a long period of time and will continue to allow us to reobserve tagged abalone over time, given the abalone remain in or near the sites.
Our results for green abalone translocation also differed from a past green abalone translocation study conducted along the mainland of southern California. Tegner (1992) translocated green abalone from Santa Barbara Island to Palos Verdes Peninsula in Los Angeles County. The results of their study showed persistence of translocated abalone and some evidence of gonad development. Similar to our study, Tegner (1992) also minimized mortality by performing predator removal at the translocation sites. In this previous translocation study, a large number of abalone were moved within a translocation site and to an area that had a very low resident population. In contrast, our study was conducted in the proximity of a more substantial green abalone population, which may have affected the persistence of translocated abalone. Throughout the study, we had a high survival rate of abalone after tagging and translocation activities. The total mortality documented in this study was less than 5% for translocated abalone compared with 10-18% in previous translocation studies (Henderson et al. 1988, Tegner 1992).
Next Steps in Translocation
The goal of translocation is to enhance local abalone production beyond local mortality. To assess the success of future translocation experiments
we would want to examine factors in addition to the maintenance of aggregation density and movement. Future monitoring goals include quantifying gonad development, larval and newly settled abalone density, and juvenile recruitment to quantify the reproductive contribution of the translocated animals. Recruitment of juveniles to the translocation sites could be compared with recruitment at control sites. Reproductive Allee effects may be contributing to the recruitment failure observed for pink and green abalone in the northern Channel Islands (Rogers-Bennett et al. 2004). Abalone recruitment monitoring has begun at Santa Catalina Island, but is not occurring at San Clemente Island as a result of restrictions on fieldwork associated with its designation as a facility of the U.S. Navy. Anecdotal evidence suggests that the recruitment of juvenile green abalone at Santa Catalina Island appears to be increasing in shallow habitats since the moratorium on fishing.
Translocation is also used to enhance abalone growth for fisheries. In some regions, short slow-growing adult abalone are moved to algae-rich habitats to promote growth. This method appears to be successful in cases in which abalone are food limited (Dixon & Day 2004). Similarly, adult translocations have been successful at increasing individual growth rates for northern abalone in Canada, where short, stunted "surf" animals are moved to protected, food-rich habitats (Breen 1986, Emmett & Jamieson 1988). More work is needed in these regions to test whether this method can be used to boost local density, thereby increasing the chances for successful fertilization (Babcock & Keesing 1999) and reproduction. There is evidence that the genetics of stunted and fast-growing abalone are similar with respect to mitochondrial DNA (Appleyard et al. 2009), suggesting these morphological differences are not genetic. Compared with translocation or aggregation of wild abalone stock, abalone reseeding programs have had different levels of success with a wide variety of recapture rates. Recapture rates include 8-38% for Haliotis discus discus (Yanagisawa et al. 1988, Kanamaru et al. 1993, Tachiyama & Futashima 1993), 17-22% for Haliotis discus hannai (Takeichi 1988, Kanamaru et al. 1993), and 12-51% for H. discus discus (Kojima 1995).
Translocation may improve growth rates, but the primary goal for depleted populations is to enhance reproductive success and overcome Allee effects for low-density populations. Although we found that pink abalone are optimal candidates for translocation based on their more sedentary behavior, which promotes the maintenance of translocated aggregations, the major hurdle for pink abalone will be to find enough of them to translocate. In many regions of southern California, pink abalone densities are so low that many hours of search time will be needed to gather animals for translocation. This was demonstrated inside our control sites at San Clemente Island, where the number of existing abalone was very low. Historic distributions of pink abalone indicated this area was more abundant in the past. The highest densities in southern California are now in the San Diego, California, region (Button 2008) and at San Clemente Island, which may make ideal locations for future large-scale pink abalone transplant work. Future translocation work should use these source areas to conduct larger scale translocations. Furthermore, more work should be done identifying source-sink dynamics of the larger metapopulation (Morgan & Shepherd 2006) so that translocations could be sited to take advantage of the local dynamics.
This study was designed to be a pilot study to test persistence at a local spatial scale (each island); thus, any population structure or genetic differentiation was conserved. Prior to conducting larger scale, longer distance translocations between islands and the mainland coast, the presence of existing differential genetic population structures at the planned translocation sites should be considered. Such information is limited at this time, but studies to determine whether there is genetic differentiation among geographic populations is currently underway (J. Hyde, NOAA Fisheries, pers. comm., 2012). The results from this work demonstrate how the behaviors of individual species of abalone need to be quantified to determine which kinds of restoration actions have the best chances of success for restoring abalone populations.
We thank NOAA Fisheries for providing funding for this project. We extend special thanks to P. Dimeo, E. Castillo, P. Hampton, and the Long Beach Aquarium of the Pacific Volunteer Scientific Divers for conducting much of the green abalone monitoring. Many CDFW staff and divers were involved, including M. Kibby, K. Lakos, C. Juhasz, R. Bartling, T. Buck, T. Mason, D. Osorio, K. Barsky, M. Prall, H. Gliniak, O. Horning, E. Jarvis, and J. Gross. CDFW enforcement provided vessel support and divers including S. Cabral, C. Corbo, S. Gilbert, R. Buckler, E. Kord, D. Sforza, J. Holemo, S. Moe, and S. Burman. P. Kalvass and T. Barnes provided manuscript editing. This is a contribution of the University of California Davis Bodega Marine Laboratory. Last, we thank the U.S. Navy, San Clemente Island, for cooperating with us during our monitoring trips.
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IAN K. TANIGUCHI, (1) * DEREK STEIN, (2) KAI LAMPSON (2) AND LAURA ROGERS-BENNETT (3)
(1) California Department of Fish and Wildlife, 4665 Lampson Avenue, Suite C, Los Alamitos, CA 93455; (2) California Department of Fish and Wildlife, 1933 Cliff Drive, Suite 9, Santa Barbara, CA 93109; (3) California Department of Fish and Wildlife, Bodega Marine Laboratory, 2099 Westside Road, Bodega Bay, CA 94923
* Corresponding author. E-mail: email@example.com
TABLE 1. Survey results for tagged pink abalone (ab) at the Seal Cove and Fish Hook translocation sites. Preexisting Added or Found Day removed (%) ([double Density no. * ([dagger]) dagger]) (ab/[m.sup.2]) Seal Cove translocation site 0 +7 100 0.28 366 0 100 0.28 367 +1 100 0.32 667 0 75 0.24 715 0 63 0.20 757 0 38 0.12 Fish Hook translocation site 0 +3 100 0.12 1 0 67 0.08 196 +1 75 0.12 197 0 75 0.12 254 +1 60 0.12 281 0 60 0.12 329 0 60 0.12 Translocated No read Total Added or Found (%) Density density density Day removed ([double (ab/ (ab/ (ab/ no. * ([dagger]) dagger]) [m.sup.2]) [m.sup.2]) [m.sup.2]) Seal Cove translocation site -- -- -- -- -- 0.28 0 +21 100 0.84 -- 1.12 1 -1 100 0.80 -- 1.12 301 0 80 0.64 0.04 0.92 349 0 75 0.60 0.08 0.88 391 0 90 0.72 0.08 0.92 Fish Hook translocation site -- -- -- -- -- 0.12 -- -- -- -- -- 0.08 0 +14 100 0.56 -- 0.68 1 0 100 0.56 -- 0.68 58 0 100 0.56 -- 0.68 85 0 79 0.44 -- 0.56 133 0 79 0.44 -- 0.56 * Days after tagging for preexisting and translocated abalone. ([dagger]) Tagged abalone (+) or mortality (-). ([double dagger] Calculated for abalone in site from prior visit. TABLE 2. Survey results for tagged pink abalone (ab) at the West Cove and Seal Cove control sites. Found (%) Added or removed ([double Density Day no. * ([dagger]) dagger]) (ab/[m.sup.2]) West Cove control site 1 +4 100 0.16 735 0 100 0.16 826 0 50 0.08 Seal Cove control site 1 +3 100 0.12 734 0 0 0 825 0 67 0.08 * Days after tagging for preexisting and translocated abalone. ([dagger]) Tagged abalone (+) or mortality (-). ([double dagger]) Calculated for abalone in site from prior visit. TABLE 3. Survey results for tagged green abalone (ab) at the Chalk Cove and Arrow Point translocation sites. Preexisting Found Added or (%) Density Day removed ([double (ab/ no. * ([dagger]) dagger]) [m.sup.2]) Chalk Cove translocation site 0 +12 100 0.12 190 0 33 0.04 191 0 33 0.04 200 0 25 0.03 204 0 17 0.02 236 0 25 0.03 256 0 25 0.03 458 0 0 0 462 0 8 0.01 595 0 17 0.02 Arrow Point translocation site 0 +14 100 0.14 242 0 50 0.07 243 0 43 0.06 244 0 50 0.07 250 0 43 0.06 252 0 36 0.05 256 0 21 0.03 263 0 29 0.04 277 0 43 0.06 309 0 14 0.02 324 0 14 0.02 428 0 7 0.01 617 0 43 0.06 630 0 14 0.02 Translocated Found No read Total Added or (%) Density density density Day removed ([double (ab/ (ab/ (ab/ no. * ([dagger]) dagger]) [m.sup.2]) [m.sup.2]) [m.sup.2]) Chalk Cove translocation site -- -- -- -- -- 0.12 0 +51 100 0.51 -- 0.55 1 0 45 0.23 0.19 0.46 10 -1 26 0.13 0.07 0.23 14 0 20 0.10 0.10 0.22 46 0 18 0.09 0.07 0.19 66 0 14 0.07 0.11 0.21 268 0 8 0.04 0.07 0.11 272 0 2 0.01 0.02 0.04 405 0 16 0.08 0.01 0.11 Arrow Point translocation site -- -- -- -- -- 0.14 0 +62 100 0.62 -- 0.69 1 -4 40 0.23 0.10 0.39 2 0 43 0.25 0.13 0.45 8 0 33 0.19 0.14 0.39 10 0 34 0.20 0.11 0.36 14 0 22 0.13 0.11 0.27 21 0 29 0.17 0.22 0.43 35 0 14 0.08 0.09 0.23 67 0 5 0.03 0.19 0.24 82 0 5 0.03 0.07 0.12 186 0 0 0 0.07 0.08 375 0 19 0.11 0.07 0.24 388 0 2 0.01 0.08 0.11 * Days after tagging for preexisting and translocated abalone. ([dagger]) Tagged abalone (+) or mortality (-). ([double dagger]) Calculated for abalone in site from prior visit. TABLE 4. Survey results for tagged green abalone (ab) at the Blue Caverns and Arrow Point control sites. Tagged abalone % Immigrants Total Added or Found Density density density Day Removed ([double (ab/ (ab/ (ab/ no. * ([dagger]) dagger]) [m.sup.2]) [m.sup.2]) [m.sup.2]) Blue Caverns control site 0 +47 100 0.47 0 0.47 812 0 13 0.06 1.69 1.75 931 0 13 0.06 0.40 0.46 Arrow Point control site 0 +16 100 0.16 0 0.16 328 0 44 0.07 0.27 0.34 384 0 31 0.05 0.51 0.56 680 0 44 0.07 0.95 1.02 * Days after tagging abalone. f Tagged abalone (+) or mortality ([double dagger]) Calculated for abalone in site from prior visit. TABLE 5. Density with and without immigrant green abalone at the Chalk Cove and Arrow Point translocation sites. Density with Density without Day no. * immigrants immigrants Chalk Cove translocation site 0 -- 0.12 190 -- 0.55 191 0.60 0.46 200 0.46 0.23 204 0.35 0.22 236 0.34 0.19 256 0.34 0.21 458 0.28 0.11 462 0.22 0.04 595 0.23 0.11 Arrow Point translocation site 0 -- 0.14 242 0.88 0.69 243 0.47 0.39 244 0.56 0.45 250 0.48 0.39 252 0.46 0.36 256 0.36 0.27 263 0.48 0.43 277 0.36 0.23 309 0.29 0.24 324 0.24 0.12 428 0.33 0.08 617 0.43 0.24 630 0.21 0.11 * Days after tagging abalone.
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|Author:||Taniguchi, Ian K.; Stein, Derek; Lampson, Kai; Rogers-Bennett, Laura|
|Publication:||Journal of Shellfish Research|
|Date:||Apr 1, 2013|
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