Newfoundland and Labrador Aquatic Invasive Species Workshop March, 2010 Clovelly Golf Course St. John s, Newfoundland

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1 Newfoundland and Labrador Aquatic Invasive Species Workshop March, 2010 Clovelly Golf Course St. John s, Newfoundland Cynthia McKenzie 1 and Darrell Green 2 Workshop Co-Chairs 1 Science Branch Northwest Atlantic Fisheries Centre, White Hills St. John s, Newfoundland A1C 5X1 2 Research and Development Newfoundland Aquaculture Industry Association St. John s, Newfoundland A1B 4J9 Funding for this workshop was provided by the Invasive Alien Species Partnership Program (IASPP) and Fisheries and Oceans Canada

2 FOREWORD The purpose of these proceedings is to document the activities and key discussions of the 3 rd Newfoundland and Labrador Aquatic Invasive Species workshop held in St. John s on March 18-19, The proceedings include updates on AIS monitoring and research in Newfoundland, the southern Gulf of St. Lawrence and the pacific coast (British Columbia). Topics were divided into two days. Day 1 focused on green crab status and mitigation, Day 2 on tunicate and other invasive species monitoring, research and management techniques. The comments made by workshop participants, as well as monitoring, research and management priorities form the discussion and final remarks from the workshop. Interpretations and opinions presented in this report may be factually incorrect or misleading, but are included to record as faithfully as possible what was considered at the meeting. No statements are to be taken as reflecting the conclusions of the meeting unless they are clearly identified as such. Moreover, further review may result in a change of conclusions where additional information was identified as relevant to the topics being considered, but not available in the timeframe of the meeting.

3 TABLE OF CONTENTS Summary... iv Introduction... 1 Presentations... 2 Day 1 (Thursday, March 18) - Chaired by Darrell Green, NAIA Topic: European Green Crab... 2 European Green Crab, Carcinus maenas, on the Pacific Coast of Canada... 2 A History of the Green Crab in the southern Gulf of St. Lawrence... 4 Ecological Assessment of the Invasive European Green Crab, Carcinus maenas, in Newfoundland (Population Dynamics & Ecological Impact)... 4 Is Foraging by the Rock Crab, Cancer irroratus, Affected by the Green Crab, Carcinus maenas?... 8 Research on the Transferability of Green Crab Larvae with Mussel Seed and Potential Methods to Avoid Green Crab Transfers from Placentia Bay with Mussel Aquaculture Product... 9 Green Crab Mitigation: North Harbour, Placentia Bay ( )... 9 Summary from the 2010 Newfoundland Green Crab Regional Advisory Process Group Discussion and Final Remarks Day 2 (Friday, March 19) - Chaired by Cynthia McKenzie, DFO Topic: Tunicates and Other Aquatic Invasive Species Aquatic Invasive Species (AIS) Initiative Population dynamics of the invasive bryozoan Membranipora membranacea along subarctic and temperate longitudinal and latitudinal gradients Atlantic Innovation Fund - Techniques and mitigation strategies for invasive tunicate fouling Invasive tunicates and shellfish aquaculture interactions/research in British Columbia Invasive tunicates: Progress report on the Memorial University / Department of Fisheries and Oceans ascidian tunicate project and update on Belleoram violet tunicate mitigation Group Discussion and Final Remarks (Day 2) Appendix A. Workshop Participants / Annexe A. Participants à l atelier Appendix B. Workshop agenda iii

4 SUMMARY Four non-indigenous marine species have caused major concerns in Newfoundland since their discovery in 2006 and These species are the European green crab, the golden star tunicate, the violet tunicate and the lacy bryozoan. The European green crab has established itself on both coasts of North America and populations continue to spread. Research is being conducted to determine the species population dynamics, impacts to receiving environments, implications for human economics, and potential mitigation measures. Green Crab catch rates in Placentia Bay, Newfoundland are the highest of those reported in North America, and studies suggest they have the potential to negatively impact eelgrass habitat, lobster populations, native rock crab, and wild or aquaculture-grown shellfish populations. Although chemical and biological treatments have been suggested for green crab mitigation, only manual removal has been accepted as an option in Newfoundland. In the last year fish harvesters (lobster and/or eel) have been given the option of applying for green crab experimental licenses to control populations and protect vulnerable fishery resources. Fisheries and Oceans Canada (DFO)/Memorial University of Newfoundland (MUN) monitoring efforts in collaboration with fish harvesters and the Fish Food and Allied Workers (FFAW) in Newfoundland has documented the rapid spread and impact on native species and habitats by the invasive green crab in Placentia Bay and the west coast of Newfoundland. Collaborative projects have attempted the experimental mitigation and control of the green crab with reduction in numbers in some areas. The native rock crab may be negatively affected by the green crab. In some areas where green crab have been intensively mitigated, the native rock crab numbers in sample traps have increased. The introduction of non-native tunicate species into the Maritime Provinces has cause an increase in costs and labor within the aquaculture industry. Shellfish aquaculture in Newfoundland may not be able to withstand additional financial expenses associated with tunicate infestations. Tunicate monitoring through the Provincial Department of Fisheries and Aquaculture and the Government of Canada s Invasive Species Program has been ongoing for 3-4 years. To date, only 2 colonial tunicates have been identified in the Newfoundland region, and neither has been observed on an aquaculture site. Mitigation methods are under development with the primary goal of eradication, or control of growth and spread of existing populations. Research on rapid detection and mitigation methods is ongoing nationwide. A three year MUN/DFO research study is focused on invasive colonial tunicates in the Newfoundland environment, particularly on their early detection and life history to determine more effective mitigation methods. Mitigation attempts for violet tunicate in Belleoram, Newfoundland have been unsuccessful in eradication of the population; however efforts may be successful in containing the colonies within their initial area of growth. iv

5 Membranipora membranacea (the lacy bryozoan) has been observed in Newfoundland since It has become widely distributed throughout Provincial waters and may have the potential to impact large kelp bed habitats. Populations are highly influenced by temperature, and abundance tends to decrease at geographical extremes. Difficulties in mitigating against invasive species highlights the importance of prevention of introduction, early detection and spread. Preventing new introductions is easier than eradication. v

6 INTRODUCTION Since the discovery of four non-indigenous marine species in the Newfoundland region major concerns have been expressed regarding their impact on habitat, fisheries and aquaculture. In 2007 the Newfoundland and Labrador Aquatic Invasive Species Advisory Committee was formed to provide a means of direct communication between stakeholders and provide advice on priority AIS issues in this Province. Through the Government of Canada s Invasive Species Program, Fisheries and Oceans Canada, Memorial University of Newfoundland, the Provincial Department of Fisheries and Aquaculture, the FFAW, public education materials, monitoring, research and mitigation activities for invasive species in the Newfoundland region has provided information regarding aquatic invasive species in this province. On March 18-19, 2010 the 3 rd Newfoundland and Labrador Aquatic Invasive Species Workshop was held in St. John s. The purpose of this workshop was to gather representatives from various government, non-government, educational groups and industry stakeholders in an effort to communicate current issues surrounding AIS, recent research, management and survey results, and to discuss further research and management options to deal with these species. The following proceedings summarize the information communicated throughout the workshop, and information gained through discussion of national monitoring and research results, future efforts, management of invaded areas, and prevention of future spread. 1

7 PRESENTATIONS The presentations and discussions touched on several relevant areas. The first day of the workshop was dedicated to the discussion of green crab surveys, monitoring, research and management. The second day dealt with tunicates and other invasive species. Workshop participants included government, non-government and university groups from both Canadian coasts (British Columbia to Newfoundland). Day 1 (Thursday, March 18) Chaired by Darrell Green, NAIA Topic: European Green Crab European Green Crab, Carcinus maenas, on the Pacific Coast of Canada Tom Therriault Research Scientist, Fisheries and Oceans Canada, Pacific Biological Station, Nanaimo, British Columbia The European green crab (Carcinus maenas) has a native range along the western European coast to northern Africa. Green crabs have been further introduced, and maintain established populations on all major continents. Established populations are now present on both coasts of North America, and populations continue to spread. The green crab has been ranked one of the world s worst alien invaders, impacting native ecosystems (including fisheries, biodiversity and aquaculture). Green crab is thought to have been introduced to the west coast of North America (San Francisco) through packing material used in oyster shipments in From there populations expanded northward and arrived in British Columbia in 1998/1999 following El Nino events. Although peninsulas act as dispersal barriers for most species, green crabs have managed to spread beyond such barriers. Research has been aimed at: 1) predicting which areas are at risk with respect to the spread of green crab and 2) understanding why some areas support very large populations of green crab. The first dedicated trapping of green crab was in 2006 when DFO initiated the first surveys as part of the Government of Canada s AIS monitoring program. Fukui folding traps using herring as bait were used to capture green crab. Traps are spaced on groundlines 10 m apart with 6 traps per line. Results obtained for show Pipestem Inlet and Winter Harbour (west coast of Vancouver Island) as having the greatest density of green crab (as indicated by the high catch rates in the area). Areas with 0 green crab/trap were also recorded for baseline records. Green crab densities are relatively patchy. Studies are underway to determine why some areas are more susceptible to green crab establishment than others. Abundance in green crab seems to have increased from (inferred from catch rates), particularly in Pipestem Inlet. High catch rates seem to correlate with decreases in salinity. Size-frequency distributions for male green crabs show strong year classes in 2005 and 2006, but poor recruitment in Green crab tend to be larger in British Columbia than on Canada s east coast (some greater or equal to 90 mm). GARP model predictions show favorable locations for introduction and establishment along BC s outer coast. GARP models that include eastern Canada and European distributions show potential distributions along most of the Atlantic coast. Particle distribution models indicate potential for natural larval dispersal into more northern areas during the winter months. 2

8 Green crabs seem to prefer areas with some freshwater input, and tend to dominate shallow zones. Larger males overlap in the interaction zone with Cancer gracilis (BC s native graceful crab). Green crabs have broad salinity tolerances (euryhaline), and typically choose less saline zones. Recent experiments compared C. maenas vs. C. gracilis survival in different salinities. C. gracilis was much less tolerant to low saline waters and move in on saline intrusions. C. maenas does not show the same pattern. Temperature seems to be a less important factor for determining spatial distribution, whereas salinity appears to better influence local movements. The 2008 Green Crab risk assessment categorized the species as high risk for negatively impacting shellfish aquaculture, habitat and biodiversity. Tagging of green crab at Pipestem Inlet was carried out to give population estimates, and to determine moult increment. 3 floy tags were initially used, but crabs could pull the tags out (tags were too large). The tags were switched to ¾ which gave good percent recovery. Those tags placed within the suture line had good retainment. Discussion (Question Period) Laura Park: Has genetic analysis been carried out on BC green crab populations? A. The genetic lineage of green crabs introduced to the west coast may be of warmer climate populations from the east coast of the USA (Mediterranean lineage). Claudio Dibacco: In response to the discussion of the wide salinity tolerance of green crabs, they have also found in Bras d Or lake which is also very low salinity. Earl Dawe: Is there any indication of why recruitment of green crab was poor in 2007? A. Recruitment in 2007 may be attributed to it not being an El Nino year; recruitment failure was actually witnessed coast-wide, including in Washington and California. Group discussion: In response to the discussion of the very wide environmental tolerances of green crabs. There have been observations during field studies of green crabs tolerating extremes in temperatures (freezing for 24 hr), air restrictions (storage in Ziploc bags for extended periods) and very high salinities (brining). Darrell Green: What negative implications have green crab had for the aquaculture industry in British Columbia? A. The primary concern for the aquaculture industry would be the transfer of product from areas of green crab establishment. Product in areas with green crab may provide a means of secondary transport to non-affected areas. Processing methods may be used to eliminate concern of secondary spread. Some examples include internal flow through tanks, pre screening of waste and freshwater rinses. Iain McGaw: Explanation of color differences in response to environmental tolerances of green crabs. Pale green colored crabs tend to have broader environmental tolerances. Red/brown crabs moult less frequently and are physically stronger, but have lower physiological tolerances than their green counterparts. 3

9 A History of the Green Crab in the southern Gulf of St. Lawrence Erica Watson Invasive Species Research Technician, Fisheries and Oceans Canada, Gulf Fisheries Centre, Moncton, New Brunswick Much of the information from this presentation comes from The Biological Synopsis of Green Crab (Klassen & Locke, 2007). C. maenas was first recognized on the east coast of Canada in 1951 in the Bay of Fundy. Populations spread rapidly from Maine through the Bay of Fundy, yet due to the slow spread of populations to more northern locations it seemed green crab may have reached the more northern limits of their range. It took 30 years for populations to spread along the Nova Scotian coastline. Genetic studies suggest a new invasion of green crab from the northern part of the European range that may be better adapted to colder climates than the Bay of Fundy populations. Since the introduction of this new population they have again begun to spread rapidly, with populations appearing in PEI, the Magdalene Islands and Newfoundland. Range expansion is continuing into the North Humberland Strait. Dispersal rates have been calculated at a range of 1.5 to 101 km/yr. At least one unsuccessful introduction has been reported in Malpeque Bay, PEI. Several green crabs were noticed among a shipment of eels, into the area, the crabs were spotted and destroyed by fisherman. Since that time there have been no reports of green crabs in this area. Worldwide, all studied green crab invasions have shown negative effects on bivalves, some show effects on native crabs, and a few show effects on fishes. Prey preferences have been consistent, with green crabs preferring mollusks, but also feeding on other crustaceans, polychaetes and green algae. Potential adverse effects include reduction of prey densities, competition with other predators, damage to habitat and potential interference with trapnet fisheries. There have been no formal studies on green crab effects on the eel fishery in PEI, but there has been anecdotal evidence of negative impacts. Worldwide, few positive effects have been reported, including the green crabs role as a scavenger, controlling biofouling and its role in the commercial fishery (in Europe). In the southern Gulf of St. Lawrence all invasions have occurred in protected embayments. Green crab ecosystem impact research in the southern Gulf of St. Lawrence in included an assessment of effect of green crab on prey species, competitors and habitat. Estuaries in which green crabs were present showed reduced biodiversity of near shore fishes and above-ground invertebrates. Main taxa found during gut content analysis were gastropods and polychaetes. Field enclosure studies found declines in several bivalve species including soft shell clams, quahogs, oysters and mussels (especially those small in size). Nuisance species permits for capture of green crabs were issued in PEI in to protect vulnerable fishery resources (such as eels). Ecological Assessment of the Invasive European Green Crab, Carcinus maenas, in Newfoundland (Population Dynamics & Ecological Impact) Cynthia McKenzie Research Scientist, Ecological Sciences Section, Fisheries and Oceans Canada, Northwest Atlantic Fisheries Centre The European Green Crab, Carcinus maenas, was first identified in Newfoundland waters on August 23, 2007 in North Harbour, Placentia Bay. Since that time Fisheries and Oceans has focused on conducting an ecological assessment of the species in the Newfoundland region. This includes study of population dynamics, ecological impact in areas of high concentration, and potential mitigation or control methods. 4

10 Ecological assessment surveys in Placentia Bay have been combined with collaborative surveys and studies with DFO, MUN, MI, DFA, FFAW, fish harvesters and Swift Current Academy. Surveys in Placentia Bay span from Burin (on the west side of the bay) to Placentia (east side). In 2007 the known distribution of green crab in Newfoundland was from Davis Cove (western side of Placentia Bay) to Long Harbour (east side) with the largest catch rates coming from North Harbour. Samples have been analyzed (Blakeslee et al., 2010 in prep.) from North Harbour and Come by Chance. Results suggest strong genetic similarities with south and southeastern Nova Scotian populations. Figure 1: Distribution map for Carcinus maenas in Newfoundland (2007) showing areas where sample were taken for genetic analysis (NH-North Harbour, CBC-Come by Chance). Size distributions obtained from North Harbour in 2007 indicate at least 4-5 year classes, putting time of introduction prior to 2002/

11 Frequency n NH = Carapace Width (mm) Figure 2: Size frequency histogram for Carcinus maenas in North Harbour, Placentia Bay (2007) Dive transects found the majority of crabs 5-10 m from the high tide mark, with smaller numbers at 0 m and from m. To assess habitat and adaptation of juvenile green crabs a beach survey was conducted with the help of Swift Current Academy in The beach, 50 x 100 m, was divided into 10m quadrats. Students counted and recorded all species found within the quadrats. Results were presented by the FFAW and Swift Current Academy. Table 1: Green crab abundance in Placentia Bay Current models constructed for Placentia Bay (G. Han, DFO) suggest natural dispersal is possible within the bay, but recirculation patterns do not suggest large recruitment out of the bay. Surveys in 2009 found green crab distributions in Placentia Bay to be much broader (Figure 3a). * Combination of survey and reports ** More time spent in area 6

12 A B Figure 3: Distribution map for Carcinus maenas in Newfoundland (2009). A. Placentia Bay, B. St. Georges Bay. 7

13 Most of the distribution data collected in 2009 was submitted through licensed volunteers. A Rapid Assessment Survey in July 2009 confirmed the presence of green crab on the west coast (St. George s Bay), with the largest number collected in the Port Harmon area (Figure 3b). The frequency of large males was much higher than females in In 2008 a standardized longline trap study began to assess seasonal fluctuations in the population (i.e. Male:female ratios, changes in catch rates, size frequency distributions, etc). Data from 2008 and 2009 show variations in male:female ratios throughout different time periods, with sexes nearing a 50:50 ratio in September (possibly after females release their larvae/moult/mate, etc). Because of the uncertainty of whether females were overwintering in the harbour, or moving to deeper waters outside of the bay, tagging experiments were used during the fall of 2008 to track female crabs. There is concern that green crabs could have a negative impact on the native rock crab, Cancer irroratus. Areas of Placentia Bay with large green crab populations have correspondingly small numbers of rock crabs present. During 2010 a gut content analysis study found high numbers of polychaetes and bivalves, and evidence of crustacean (possibly lobster or rock crab) remains. Since polychaetes often live in the muddy sediments under eelgrass beds in the area, there is concern that digging in the beds for prey could result in significant eelgrass damage. Aerial photos of eelgrass beds taken in 2009 in North Harbour and Swift Current were compared to previous eelgrass surveys in the areas and declines in eelgrass habitat over time have been noted. Habitat surveys also show large empty clam beds, and anecdotal reports suggest predation on small scallops. Is Foraging by the Rock Crab, Cancer irroratus, Affected by the Green Crab, Carcinus maenas? Kyle Matheson Masters Student, Memorial University of Newfoundland, Ocean Sciences Centre Green crabs have been present on the east coast of North America since the early 1800 s. Their range expanded northward into the Canadian east coast by Green crabs were identified in Newfoundland waters in 2007 (Placentia Bay) and on the west coast in The objective of this study is to investigate the effect of crab size, prey size and density, and cold water temperatures on patterns of intra- and inter-specific crab competition for a common prey species, the blue mussel. Consumption rates are determined by manipulation of 4 factors (autonomy, chemical cues, multiple predators and prey density). All experiments were repeated at 2 temperatures (12 and 4 degrees Celsius). Results indicate that warmer temperatures lead to greater consumption rates in both crab species. Green crabs were found to consume the same number of mussels as rock crabs despite the larger size of the rock crabs used in the experiments. Injured crabs did consume fewer mussels although this result was not statistically significant. Chemical cues (presence of green crabs) did not affect consumption rates or foraging behavior of rock crabs. No emergent multiple predator effects were found (inter-specific interactions were equal to intra-specific interactions). This indicates that these species may be able to co-exist when prey is abundant. However, when prey is limited green crab would be the more successful predator. In lab based trials green crabs were first to the prey species in more trials than the rock crab (independent of temperature). More emphasis is required to study foraging and subsequent behaviors of more vulnerable juvenile populations of rock crab under various abiotic and biotic variables and in the natural environment. 8

14 Research on the Transferability of Green Crab Larvae with Mussel Seed and Potential Methods to Avoid Green Crab Transfers from Placentia Bay with Mussel Aquaculture Product Kiley Best Masters Student, Marine Institute of Memorial University Currently Newfoundland is experiencing a Provincial shortage of mussel seed. The main mussel industry is based in Green Bay, and potential exists to transfer seed to Green Bay from Placentia Bay. With green crab present in Placentia Bay (although not observed on any farm sites) there is concern that transfer of aquaculture product from the bay could provide a secondary mode of transport for introduction to non-affected regions. This study will investigate the possibility of green crab larvae transferability with mussel seed. Green crab larvae will be tested to determine if they prefer to settle on or within mussel seed, and then examine the most economical and efficient methods of mitigation. The goal is to ensure mussel seed can safely be transferred from Placentia Bay to Green Bay. Initial results from this study include GSI measures which indicate Newfoundland green crabs are maturing at a smaller than normal carapace width. In 2010 initial techniques will be modified and larval spawning experiments will be conducted during the summer. Green Crab Mitigation: North Harbour, Placentia Bay ( ) Janice Ryan Fish Food and Allied Workers Union An aquatic invader is a term used to describe a non-native species, who when introduced to a new environment will likely cause damage to the host ecosystem, existing species, the economy or human well-being. Invasive species can thrive in the absence of their native predators and have the potential to drastically alter habitat, rendering it inhospitable for native species. Green crabs were discovered in North Harbour, Newfoundland by local fish harvesters in the fall of Fishermen in the area described seeing the same crab species in the area in Following the 2007 report, DFO initiated the first green crab research study for the Newfoundland region. In February of 2008, DFO held a national AIS green crab risk assessment which concluded that green crab are a high risk invader for Canada. The DFO surveys gave an estimation of the population distribution in Placentia Bay (Long Harbour to Davis Cove). The highest concentration was observed in North Harbour and the population appeared to have significant negative impacts on both eelgrass beds and molluscs in the area. Due to the large green crab population in the North Harbour area, this area was chosen for initiation of a mitigation attempt in The mitigation plan implemented a 3-pronged approach 1) directed fishery, 2) AIS education program, and 3) research and science. The mitigation was received very positively and was supported by cooperation with the North Harbour Harbour Authorities, the community, and local fish harvesters. A junior stewardship program (with the help of Swift Current Academy) took place in 2008 and included an education session, beach transect survey, sample and data analysis and presentation. For the directed fishery North Harbour was divided into 4 fishing areas. 1) residential portion of North Harbour, 2) Goose Cove, 3) west side of the head of the bay, and 4) east side of the head of the bay. The 2008 mitigation took place through July 23-August 8, September 8-19 and September 29. Four licensed fish harvesters were selected out of 15 that applied to carry out the mitigation. Modified snow crab pots and folding Fukui traps were used. Previous surveys found larger animals tended to stay in relatively shallow depths; therefore the mitigation was targeted toward preferred habitat. CPUE s were higher when the larger modified snow crab pots were used. 9

15 Area 3 supplied the largest number of individual crabs of all areas (Table 1), and areas 3 and 4 had the largest number of crabs per trap (CPUE). CPUE in the North Harbour area (1) declined from July to September of Table 1. CPUE (craps per trap) calculated from the North Harbour mitigation attempt in AREA Total Individuals AREA 1 35, 230 AREA 2 108, 433 AREA 3 177, 528 (50% of total catch) AREA 4 27, 937 The mitigation resumed in July of 2009 for a period of three weeks in areas 1 and 2. Number of individual crabs caught, and CPUE were lower in area 1 than 2. Also in 2009, volunteers were allowed to apply for green crab experimental licences to aid in collecting distribution and population information (Table 2). Table 2. Number of green crab and calculated CPUE for volunteer mitigation collections (2009). Location # Green Crab Caught CPUE Big Southern Harbour Arnold s Cove Come by Chance Little Sandy Harbour * Southern Harbour Great St. Joseph s Little Harbour West Bittern s Cove Rocky Cove Clay Cove Mooney s Point Cocks and Hens Cove Black River Swift Current Long Harbour There is hope of continuing the program in A project to determine effect of green crabs on scallops and refugia has also been proposed. 10

16 Summary from the 2010 Newfoundland Green Crab Regional Advisory Process Cynthia McKenzie Research Scientist, Ecological Sciences Section, Fisheries and Oceans Canada, Northwest Atlantic Fisheries Centre On March 17, 2010 a green crab regional advisory process (RAP) was held in St. John s, Newfoundland with the objective of providing a science advice report for managers detailing green crab population and mitigation information in the Newfoundland region. The meeting was chaired by Earl Dawe, and input was given from other regions. The Newfoundland and Labrador region AIS Science Strategy is based on the AIS Rapid Response Framework developed with regional collaboration within Fisheries & Oceans Canada (Locke et al 2007, 2009) Mitigation options include containing the problem to a given area, suppress the population to slow its spread, develop management strategies to keep the species at abundances below an economic or ecological threshold or learn to adapt with the problems caused by the species. Due to the abundance of green crab in Newfoundland, there is concern of spread by secondary vectors. During the green crab mitigation workshop in February 2008 recommendations were made to research mitigation methods including 1) removing green crab using local fish harvesters and 2) beach clean up programme by community or school groups in affected areas. From the first 2 phases of the pilot fishery in 2008 more than lbs of green crab were collected, with an additional 6000 lbs collected during phase 3 in Significant declines in catch rates were seen in both areas 1 (North Harbour) and 2 (Goose Cove). However, catch rates declined faster in area 1 than area 2. Mean weight and size (carapace width) of crabs also decreased in areas 1 & 2 over time. Since removal of reproductive females was one goal of the mitigation, sex ratios were monitored through subsamples throughout the mitigation. Sex ratios fluctuated throughout the pilot fishery. Decreased female trapability seemed to correlate with reproductive cycles (i.e. less attracted to traps when ovigerous, moulting or mating). Seasonal changes in population structure require further study to determine the most effective periods for maximum trapability. Data from standardized longline surveys in area 2 (Goose Cove) were used to compare removal of green crabs with bycatch presence. Results show a decrease in overall number of green crab trapped over time ( ), and an overall increase in number of rock crab bycatch trapped at the same time period. In an attempt to determine juvenile distribution and shoreline biodiversity in areas of high green crab presence, a beach survey was conducted with the help of Swift Current Academy on September 29, The survey included collecting and recording specimens from beach transect, trapping and beach seining. Results confirmed the presence of young juvenile crabs within the intertidal zones hiding among kelp and rocks. Species biodiversity was low in areas with high numbers of green crab. Experimental licenses were developed and provided by DFO to interested licensed lobster or eel fishers to mitigate or attempt to control green crab. Fukui traps were provided by DFO Science and participants were required to keep log books recording catch weight, bycatch and habitat data. Twenty experimental licenses were provided by request in Catch rates were again highest in the northern portions of the bay (Figure 1). One determined fisherman in Long Harbour consistently removed green crabs from the harbour for a one month period every 24 hours. An estimated 25,000 crabs were taken from the area in a one month period. Data from the area show a decreasing trend in the CPUE (crabs/pot/hour) over that time period. 11

17 Figure 1. Experimental green crab volunteer license results (2009). Recommendations for future research include: 1. To determine density of green crabs in areas with high CPUE. This will aide in determining the proportion of crabs removed during mitigation attempts. 2. Continue research on impacts of green crabs on fragile marine habitats, especially relating to eelgrass habitat, rock crab/green crab interactions, etc. 3. Continue existing survey and monitoring programs to provide useful information on green crab populations which can be used to determine what management options should be in particular areas and where time, effort and resources would be best utilized. 4. Try to determine the green crab density threshold to which populations can begin to negatively impact the environment to which they are introduced. 12

18 Group Discussion and Final Remarks To manage invasive species, such as green crab, in NL it is necessary to evaluate their impacts in terms of the economy and the environment and ensure that management efforts are targeted at areas of greatest impact. Estimates of the economic or environmental effect or impact of invasive species could also give policy makers an idea of the scale of resources needed to effectively manage these species. Green crab are currently not considered a direct threat to the aquaculture industry in Newfoundland as most cultured species in the Province are grown off bottom. A threat remains in areas where bottom culture is used (for example manilla clam operations in BC). There is concern that green crab larval or juvenile transfer could occur, so aquaculture may be affected through limitations on introduction and transfer operations. Estimation of the economic impact of green crab may be difficult at this time. Direct economic impacts may be difficult to quantify as the most destructive effects of green crab invasion on introduced habitats and native species often occur indirectly. Although indirect impact may be great, assigning it a quantitative value is difficult and the role of determining socio-economic estimates has not been assigned to DFO Science. Short term effects may be uncertain, however delaying mitigation until long term effects can be quantified could result in irreversible changes to habitat and/or fisheries resources. A study to determine the impact on the benthic habitat, is being conducted for the North Harbour area (M. Rossong). General observations made by diver transects through eelgrass beds confirm green crab presence in eelgrass habitat and can provide some information on species interaction. Loss of eelgrass by green crab disturbance may be permanent and cause changes in sediment and benthic communities (irreversible ecosystem change). A lag in the effect of mitigation efforts that have been applied in Newfoundland in areas with high populations of green crabs may occur. The removal of larger crabs in the first stage of the mitigation may be followed by higher catch rates of smaller (newer recruits) in later stages. Consistent removal followed by periods of poor larval recruitment should cause a significant decline in the population over time. At present green crabs collected through mitigation efforts are sent for disposal. Potential uses are being discussed and include use in pelleted fish foods (potential supplement / additive) or in organic fertilizers. 13

19 Day 2 (Friday, March 19) Chaired by Cynthia McKenzie, DFO Topic: Tunicates and Other Aquatic Invasive Species Aquatic Invasive Species (AIS) Initiative Darrell Green Research and Development Coordinator, Newfoundland Aquaculture Industry Association Since 2006, the Newfoundland Aquaculture Industry Association (NAIA) has expressed concern regarding the introduction of invasive marine species into regions of the Province currently used (or of potential use) in the aquaculture industry. There is concern that AIS could affect shellfish and finfish aquaculture, fisheries and regional biodiversity. AIS have been present in Atlantic Canada for decades, and introduction has been primarily attributed to movement of shipping traffic. Since Newfoundland has a vibrant shipping industry, the threat of introduction of AIS to the Newfoundland region is very real. AIS can impact aquaculture, fisheries, and regional habitat in a variety of ways (often depending on the species being introduced). Although not a human health or food quality concern, tunicates have been found to foul gear (ropes, buoys, etc), increase handling and processing costs of seafood products (especially shellfish), or they may deter or slow shellfish spat settlement. Other species (such as the green crab) may eat cultured shellfish. Aquaculture ventures in NL are small enterprises and may not be able to financially withstand the negative impacts of an introduced invasive species. In 2006 NAIA received funding through the Government of Canada s Invasive Alien Species Partnership Program (IASPP). The program was initiated in February of The IASPP initiative included an educational campaign, and formation of a regional advisory committee. Species of interest to the NL IASPP initiative include tunicates, algae and crustaceans. Solitary tunicates, such as the clubbed and vase tunicates, have not yet been identified in Newfoundland. They are heavy fouling species which can strip mussel lines during harvest of product. Colonial tunicates, like the golden star and violet tunicate, have been identified in Newfoundland in recent years. The violet tunicate was first identified in Belleoram Harbour in 2007, however has not been found in other Newfoundland bays. There is concern that other aggressive fouling species, such as Didemnum vexillum, may also be transported into Newfoundland waters. Didemnum vexillum is thought to originate from Japan, it was identified in Maine and Connecticut in the 1970 s and on George s Bank since None of these tunicate species have yet been found on aquaculture sites. The green crab is also of concern. This species was identified in Newfoundland in 2007, and is easily identified by 5 distinct pointed spines on either side of the carapace. Although often referred to as green crab its color can range from red-orange to green. Also included in the initiative is the large green algal species Codium fragile. This species may grow over kelp beds that had been grazed on by sea urchins. Species often found in kelp beds (lobster for example) prefer not to live in areas occupied by Codium sp. Membranipora membranacea has also currently been added to the list of species of interest. Population dynamics of the invasive bryozoan Membranipora membranacea along subarctic and temperate longitudinal and latitudinal gradients Scott Caines Masters Student, Memorial University of Newfoundland, Ocean Sciences Centre Membranipora membranacea is a widely distributed bryozoan that commonly grows on kelps and other algae. The species is believed to be of northeast pacific origin, was introduced to the 14

20 eastern USA, and from there migrated north. It has a long lived planktonic stage which may increase its ability to maintain a wide natural distribution. Other transportation vectors which may enhance its spread include ballast water release and hull fouling. M. membranacea has a reputation for outcompeting local epiphytes, reaching coverages of 60-80% of kelp surface area. It can also reduce kelp spore output, photosynthesis, growth rates, pigment concentration and nutrient uptake. Growth of this species on native kelps can cause kelp brittleness, which can lead to wave induced defoliation (up to 90% canopy loss according to Lambert et al, 1992). It was first identified in Newfoundland waters in 2002 on the west coast near Bonne Bay. Current distribution of the species throughout the island extends from Red Bay, Labrador to the Avalon Peninsula. This species population dynamics is highly dependant on sea temperature (including larval recruitment and growth). Colonies tend to be larger and wider during cooler temperatures. Research objectives for this study are 1) to investigate spatial and temporal variability in the population dynamics of M. membranacea along NL s longitudinal and latitudinal gradients and 2) examine how this variability relates to changes in sea temperature. In 2008 spatial and temporal variability was investigated along a 500 km latitudinal gradient on the west coast of Newfoundland. Local fish harvesters were hired from each site to sample the kelp Saccharina longicruris monthly from August to October. The participation of local fish harvesters was very important to the study and allowed examination of samples from a higher spatial and temporal resolution than would be capable if specimens were collected by an individual research team. Recruitment patterns were also quantified using PVC panels suspended at 6-8m depths. In 2009 inter-annual variability in Membranipora s population dynamics at two sites along Newfoundlands west coast was investigated. Patterns on Newfoundlands east coast were also investigated to see how they vary to that of the west. Data loggers were deployed at each site to monitor temperature. Results indicate that this species prefers to settle on areas of newest growth of kelp blades. This may be beneficial to the bryozoan (reduced competition with other epiphytes, and increased time to grow and reproduce). Settlement of new recruits occurs primarily in September, October and November; with significantly less recruitment in August. Abundance of settlers and recruits was highly variable both spatially and temporally. The abundance of settlers and recruits was lowest at geographical extremes. Settlement decreased with increases in latitude. Recruitment was highest at Norris Point (west coast of the island), where temperatures were highest. Very large temperature fluctuations in Port aux Basques may prevent colonies from establishing. Abundance of settlers was higher in 2009 than 2008 on the northern peninsula, despite lower mean sea temperatures in Northerly locations, which are typically more exposed geographically, seem to be more inhospitable for M. membranacea establishment. This suggests the species may be nearing the northern limits of its distribution. PVC panels were useful for examining recruitment patterns, but may more accurately represent patterns over a 2 week scale. Future research objectives include examination of spatial and temporal patterns in percent cover and abundance of adults, investigation of spatial and temporal patterns in zooid morphology and determination of the effect of water temperature on growth and morphology. Discussion (Question Period) Don Deibel Could you comment on how this species has spread around NL since 2002, knowing the biology of the species? This species relies mainly on natural means, such as oceanic currents, for dispersal, although it has been known to live on boat hulls where it could release eggs into receiving waters. 15

21 Monitoring for tunicates in the southern Gulf of St. Lawrence Erica Watson Invasive Species Research Technician, Fisheries and Oceans Canada, Gulf Fisheries Centre, Moncton, New Brunswick Four non-native tunicate species have been identified in the southern Gulf of St. Lawrence (sgsl) (vase, golden star, violet and clubbed tunicates). Public reporting is an important part of the monitoring program in the sgsl. As part of a stewardship initiative signs have been created and posted at wharves and marinas providing information related to invasive species and contact information for reports. Reports are followed by a field survey when possible. PVC plates (10cm) have been used for 3-4 years for tunicate monitoring in areas considered at high risk of AIS introduction. High risk areas include shipping ports, processing plants (lobster and mussel), fishing ports (especially Herring and Tuna) and priority areas for management advice (e.g. For Introduction and Transfers). Plates are deployed during June to August and all plates are retrieved in October. Plates are briefly examined in the field and are then preserved and analyzed in the lab. Rapid assessment surveys are also used to determine species presence. Since 2008 a set of standard sampling techniques, including visual observations of growth on buoys and the undersides of wharves, has been used. The current distribution of tunicates in PEI spans most bays on the northern, eastern and southern coasts of the island. Distribution maps produced by Fisheries and Oceans which highlight affected areas are used in introductions and transfers decisions. Several research projects are ongoing to develop monitoring protocols for tunicates in the region. One project is attempting to develop mathematical models to try to improve survey protocols using search theory (Kanary et al 2010). Dispersal vectors are also being studied. Oceanographic modeling using a horizontal resolution of 200m, boaters survey (including analysis of the effectiveness of paints and common hull antifouling materials) and examination of fouling on mobile species such as lobsters and crabs are being examined. Dispersal of tunicates by oceanographic currents is dependent on life stage characteristics. Larval dispersal ranges from 5 days (for solitary tunicates) to 2 days (for colonial types). Adult colonies can withstand longer periods in the open water drifting on buoys, floating vegetation, etc. Boating vectors in PEI, and effectiveness of hull antifouling materials were examined by Masters Student Emily Darbyson (Darbyson et al. (2009), Aquatic Invasions 4(1)). Of the boating vectors analyzed in this study, recreational boats tended to move around most often, spending short periods of time in port before moving to another destination. Of the antifouling methods used, the vessels with well maintained antifouling paints were most effective in preventing clubbed tunicate settlement. Unpainted aluminium hulls were often the most affected. In 2005 a pilot study was conducted to determine dispersal potential of tunicates on mobile species (especially crustaceans). Of the 57 lobsters and 150 rock crabs sampled, only 1 lobster was found with B. schlosseri growth. About 1/3 of the rock crab population had growth of the small solitary tunicate Molgula sp. (Bernier et al. (2009), Aquatic Invasions 4(1)). Marine users are urged to report sightings of invasive species, to wash boats and marine equipment, remove fouling from hulls, drain their bilge water in a safe area (preferably on land), let equipment dry completely and use antifouling paints on boat hulls. Discussion (Question Period) Cynthia McKenzie, Don Deibel and Erica Watson: There has been some incidence of colonial tunicates not settling on PVC in both Newfoundland and Gulf Region sites; but would settle on 16

22 associated rope, weights, etc. Evidence from some Newfoundland sites suggests that some fabrics / plastics may provide good over-wintering habitat for golden star tunicates. Atlantic Innovation Fund - Techniques and mitigation strategies for invasive tunicate fouling Jennifer La Rosa PEI Aquaculture Alliance Four tunicate species of concern have been identified in PEI (the clubbed, vase, violet and golden star tunicates). Tunicates in the PEI region have impacted the mussel aquaculture industry on both the farm and plant levels. Affected farms typically have thicker, heavier mussel socks which require the purchase of new equipment designed for lifting, cleaning and treating lines. There is also a need for new husbandry practices, issues with waste disposal, increased trucking and changes in harvesting calls. Through the Atlantic Innovation Fund the PEI Aquaculture Alliance has secured funding for a 4 year project to enhance methods for the sustainable and efficient management of tunicates. The project is subcontracted to the University of PEI and includes industry involvement. The project has multiple funding partners and collaborators. The project includes 3 modules: 1. Early Detection Includes the development of tunicate diagnostic kits (molecular, both DNA and RNA) that can be used on aquaculture farms and in the field. Currently the kits can detect 10 larvae in seawater. There is also potential to detect RNA degradation (to determine tunicate mortality). 2. Prevention Development of natural antifouling compounds to prevent tunicate growth on submerged structures. Preliminary results suggest that 6 of the tested compounds have significant antifouling properties. Work is ongoing on the structural ID of pure compounds. 3. Treatment Development of new tunicate treatments, mitigation strategies and field tests. This research is currently being lead by Dr. Jeff Davidson (Atlantic Veterinary College). Examples of trial tests include the use of Virkon aquatic & perforation (successful in tunicate treatment trials), electrochlorination & ultrasound (potential treatment options), chili pepper extracts, cellulose & siltation (failed treatments), and formic acid (undetermined effect). High pressure water treatments are currently used in the industry (primarily for Ciona sp.). Treatments must be applied at optimal times and at an optimal frequency to be effective. The project examined high pressure treatments applied in early July (2 weeks after 1st appearance of tunicates) and every 3 weeks thereafter for 5 treatments. Greater numbers of treatments correlated with increased mussel growth. Mussels treated 3-5 times had 3 to 5 times the mussel density of those untreated. Colonial tunicates have also been treated using high pressure. These treatments produce a reduction in tunicate mass, but success rate is based on timing of treatments, not frequency. Information related to tunicate treatment methods and background information on tunicates in PEI can be found in the Aqua Info Note. 17