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South coast herring (depleted or rare species) within the PBGB LOMA Potentially Harmful Activity (X) Fishing Other harvest Seabed alteration Coastal alteration Disturbance Bottom trawl Scallop dredges Clam dredges Midwater trawl Gillnets (bottom) Gillnets (pelagic) Longline Seine (pelagic) Recreational cod fishery Crab pots Lobster pots Whelk pots Other (specify) Potentially Harmful Stressor (X) Marine pollution X X Otter trapping Seal hunt Seabird hunt Seaweed harvest Anchor drops/drags Ore spill Fish offal dumping Finfish aquaculture Dredge spoil dumping Dredging Climate Change Mining/Oil & gas drilling Cables Freshwater diversion Subtidal construction Intertidal/coastal construction Harmful species Other (specify) Vessel traffic Ship strikes Ecotourism Marine construction Seismic surveys Navy sonar Other (specify) Oil pollution Industrial effluent Fishplant effluent Sewage Historic military waste Long range transport of nutrients Acid rain Persistent Organic Pollutants ( ) Eutrophication X Ghost nets Litter Other contaminants (specify) Ice distribution X Temperature change Sea-level rise Ocean acidification Current shifts Increased storm events Increased UV light Oxygen depletion Changes in freshwater runoff Other (specify) Green crab X X Membranipora Golden Star Tunicate Violet Tunicate Vase Tunicate Codium fragile Clubbed Tunicate Didemnum Harmful Algal Blooms Disease organisms (human waste) Disease organisms (aquaculture) Other (specify) Other 1 Background Information Atlantic herring are a pelagic schooling species that occur on both sides of the North Atlantic (Scott & Scott, 1988). Several stock complexes of Atlantic herring are recognized in the Newfoundland and Labrador region. Most are resident populations that spawn in coastal waters, while others exhibit only seasonal overwintering migrations into the region (Wheeler & Walsh, 2008). Unlike other pelagic species, Canadian Atlantic herring populations are comprised of both a spring and fall spawning component. Stocks in the Newfoundland and Labrador region have historically been dominated by spring spawning herring, however, autumn spawning herring have recently increased in most areas (Wheeler et al., 2009). Wheeler and Winters indicate that Atlantic herring stocks on the south and east coasts of insular Newfoundland are best defined during spring spawning when each of the large bays contain their own discrete spawning groups that exhibit homing behaviour (Wheeler & Winters, 1984). The extent to which these historical migration patterns to spawning, wintering, and feeding grounds are presently adhered to is unclear. Herring growth rates declined in the 1990s and have remained below average (Wheeler et al., 2008). Fecundity increases with increasing body length in Atlantic herring up to a maximum age and then the number of eggs produced declines (Scott & Scott, 1988). Atlantic herring are demersal spawners, depositing their adhesive eggs on stable bottom substrates, forming a carpet several centimetres thick (Reddin et al., 2002; Wheeler et al., 2009). Spawning may occur in offshore waters (i.e., Georges Bank) at depths of 40-80 m, however, most Atlantic herring stocks spawn in shallow (< 20 m) coastal waters. Coastal spawning generally occurs in shallower water in the spring (< 10 m) than in the fall (Ahrens, 1993; Wheeler & Winters, 1984) Atlantic herring are primarily pelagic and often form schools, particularly prior to spawning (Scott & Scott, 1988). Along the Canadian coast, spawning may occur anywhere between April-October, but tends to be concentrated in May and September for spring and fall spawners, respectively (Scott & Scott, 1988). In Newfoundland, spring spawning generally occurs in April to mid-June, while fall spawning occurs from mid-July to September (Melvin et al., 2009; Scott & Scott, 1988; Wheeler & Walsh, 2008; Wheeler et al., 2009; Zheng, 1996). Spawning occurs in spring in inshore shallows while fall spawning occurs in deeper offshore waters. Due to colder water, spring spawned eggs require about 30 days to hatch, while fall spawned eggs hatch in about 10 days, and larva are pelagic (Scott & Scott, 1988). There is a higher fecundity of fall spawners which is related to a decrease in the size of the yolk, which is an adaptation to warmer waters and increased likelihood of survival associated with autumnal spawning. In the Newfoundland and Labrador region, it is estimated that fecundity ranges from 12,720 eggs for a 27.8 cm, spring spawning female to 241,630 eggs for a 37.0 cm, fall spawning female (Scott & Scott, 1988). In a laboratory environment Atlantic herring upper temperature range is 19.5-21.2ºC and the lower lethal temperature is 1.1ºC. Atlantic herring are visual feeders, consuming plankton during daylight hours, filtering out the small organisms with their long, well-developed gill rakers (Scott & Scott, 1988). 2 Prior to the 1960’s, Atlantic herring were caught in most areas of Atlantic Canada by small inshore boats using gillnets, traps, or weirs (Ahrens, 1993). From 1965-1972, herring catches in Canadian waters increased rapidly due in part to the introduction of a fleet of large purse seiners, however, total catches have declined considerably from record levels obtained in the 1970’s (Ahrens, 1993). A fungal (Ichthyosporidium hoferi) infection killed many herring between 1954-1956 and increased catches of herring in the southern Gulf of St. Lawrence and the west and south coasts of insular Newfoundland during the mid-1960’s to early 1970’s were believed to have resulted from strong year-classes produced in the wake of the die-off. Year-classes produced during the 1990’s were generally small, contributing to the overall decline in abundance on the south and east coasts and as a conservation measure, certain bays on the west coast are protected from fishing during the spawning season (Wheeler & Walsh, 2008; Wheeler et al., 2008). Good survival (recruitment) of young herring is largely influenced by suitable environmental conditions, principally ‘warm’ overwintering water temperatures and ‘high’ salinities prior to spawning (Winters et al., 1986). Ideal conditions seldom exist in the region and consequently strong recruitment is very sporadic (Wheeler et al., 2008). Gillnets (pelagic) Directed herring fisheries utilize pelagic gillnet, purse seine, bar seine and traps, with purse seine being the dominant gear type. Total herring landings in the LOMA averaged 1095.5 T (1998-2007) and made up only 1.43% of total landings for the LOMA (Fisheries and Oceans Canada, 2008). Currently, herring captured in pelagic gillnet fisheries on the south and east coasts of the island are used primarily for bait in the lobster and snow crab fisheries (Reddin et al., 2002). Since total herring landings in the LOMA are relatively low, and purse seines are the dominant gear, impacts of pelagic gillnets are considered minimal. Screened out. Purse seine Herring are largely fished as schools migrate inshore to spawn. Purse seine is the dominant gear type targeting herring within the LOMA, and the northeast coast is the major focus of the fishery - of the 216 Purse seine licences issued in 2007, only 22 were issued for the south coast (St. Mary’s Bay-Burgeo) (Wheeler & Walsh, 2008). Commercial catch rates are largely market driven and the Total Allowable Catch is generally not taken. For example along the south coast, 169 tonnes were landed in 2007, 34% of the TAC (Wheeler et al., 2008). Since recruitment of herring is largely influenced by environmental conditions, and catch rates for south coast herring are consistently below the TAC, purse seines are not considered to be a key threat to the stock. Screened out. Industrial effluent: During the winter of 1969, a series of extensive herring mortalities occurred in Placentia Bay. The dead herring were red in colour (fins and body) and attracted much publicity. Mortality was found to be the result of industrial pollution, mainly phosphorus from an industrial plant (Scott & Scott, 1988) in Long Harbour. This is the current site of a planned Nickel refinery (hydromet). Although the industrial plant is closed, phosphorus piles still remain. If there were to be a repeated accident in Long Harbour, the effects to the marine life are unknown and difficult to predict, but likely would be localized. Screened out. 3 Ghost nets: Herring are a highly mobile species which travel in large schools which may result in high mortalities when a ghost net is encountered. Ghost nets are fishing gear that have been lost or discarded at sea. Since the 1960s, fishing nets have been constructed from highly durable plastic materials such as nylon, polypropylene and polyethylene, which do not biodegrade. As a result, lost nets can continue to fish for years; in deep water nets such as gillnets can drift in the currents, held in position by buoys on top and lead rope on bottom. As the nets become heavy with entangled fish, seabirds and marine mammals, the nets sink, often to the bottom, but can float freely again once decomposition has lightened their load. Nets eventually snag on bottom features and remain on the bottom where they can continue to capture scavenger species attracted by the bait provided by the previous catch. Gillnets are the gear type most frequently associated with ghost nets, but lost pots, long lines, traps, seines, trawl nets and even net or rope fragments can cause significant damage to marine ecosystems. Due to the dynamic nature of the environment, significant loss of gear has occurred. Clearly ghost nets posed a significant threat to many marine ecosystems including the spawning activity of species such as cod, cunner, plaice, and other species, and although the use of gillnets has declined, possibly leading to a reduction in the incidents of lost nets, DFO marine debris surveys (Fisheries and Oceans Canada, 2005) found significant accumulations of fishing-related items including netting fragments, rope, and buoys in the ocean, indicating that lost gear is still a concern. There is no evidence that significant numbers of Atlantic herring are caught in ghost nets. Screened out. Temperature change: Drinkwater (Drinkwater, 2005; UNEP and UNFCCC, 2002) predicts a temperature increase of 2-4oC in Southern Newfoundland waters by 2100, based on IPCC 2001 models (UNEP and UNFCCC, 2002). An increase of 0.4oC is likely the most we can expect over the next ten years based on this model. This is an average change and will be characterized by temperature fluctuations over a wider range, particularly in shallow coastal waters. Atlantic herring within the Newfoundland region are at the northern extent of their geographic range. Ideal conditions seldom exist and consequently strong recruitment is very sporadic. It has been shown (Winters et al., 1986) that when good survival of young herring (i.e. recruitment) occurred through the 1960's to 1980's, it was largely influenced by suitable environmental conditions, principally warm over-wintering water temperatures and high salinities prior to spawning. A minor increase of less than 0.4oC in average sea temperature over the next ten years is likely to be beneficial - higher temperatures increase the metabolism of fish (see review of (Blaxter, 1992)), resulting in increase growth, and fecundity, provided that the species temperature range preferences are not exceeded. Because local effects of climate change are difficult to predict, and may be characterized by an increase in temperature fluctuations, and erratic weather patterns, and environmental conditions are thought to be the major determining factor in herring recruitment in the LOMA further analysis of this stressor is warranted. Screened in. 4 Oxygen depletion: Atlantic herring, Clupea harengus, spawn demersally in discrete locations to which there appears to be a considerable degree of homing. Herring spawn in inshore demersal sites, and eggs adhere to sediments. Low oxygen can interfere with nutrient release from sediments and affect primary production, but this is not considered a major factor affecting Atlantic herring within the LOMA. Screened out. Key Activities/Stressors: Temperature change Reference List 1. Ahrens, M. A. (1993). Underwater World: Atlantic herring. Ottawa, Department of Fisheries and Oceans. Ref Type: Pamphlet 2. Blaxter, J. H. S. (1992). The effect of temperature on larval fishes. Netherlands Journal of Zoology, 42, 336-357. 3. Drinkwater, K. F. (2005). The Response of Atlantic cod (Gadus morhua) to future climate change. ICES Journal of Marine Science, 62, 1327-1337. 4. Fisheries and Oceans Canada. (2005). Marine Environmental Quality Atlas. Ref Type: Unpublished Work 5. Fisheries and Oceans Canada. (2008). 1998-2007 3LMNOP4R Effort and Catch. Policy and Economics Branch. [Newfoundland and Labrador Region Catch and Effort]. Fisheries and Oceans Canada. Ref Type: Data File 6. Melvin, G. D., Stephenson, R. L., & Power, M. J. (2009). Oscillating reproductive strategies of herring in the western Atlantic in response to changing environmental conditions. ICES Journal of Marine Science: Journal du Conseil, fsp173. 7. Reddin, D. G., Johnson, R., & Downton, P. (2002). A study of by-catches in herring bait nets in Newfoundland, 2001 (Rep. No. 2002/031). Canadian Scientific Advisory Secretariat. 8. Scott, W. B. & Scott, M. G. (1988). Atlantic Fishes of Canada. Canadian Bulletin of Fisheries and Aquatic Sciences, 219. 9. UNEP and UNFCCC. (2002). Climate Change Information Kit. Ref Type: Generic 10. Wheeler, J. & Walsh, R. (2008). NL Region: East and Southeast Coast Herring FRCC Briefing, Fisheries and Oceans Canada. 5 11. Wheeler, J. P., Purchase, C. F., Macdonald, P. D. M., Fill, R., Jacks, L., Wang, H. et al. (2009). Temporal changes in maturation, mean length-at-age, and condition of spring-spawning Atlantic herring (Clupea harengus) in Newfoundland waters. ICES Journal of Marine Science: Journal du Conseil, fsp117. 12. Wheeler, J. P., Squires, P., & Williams, P. (2008). An Assessment of Newfoundland East and South Coast Herring Stocks to the Spring of 2008 (Rep. No. 2008/070). 13. Wheeler, J. P. & Winters, G. H. (1984). Migrations and stock relationships of east and southeast Newfoundland herring as shown by tagging studies. Journal of Northwest Atlantic Fishery Science, 5, 121-129. 14. Winters, G. H., Wheeler, J. P., & Dalley, E. L. (1986). Survival of a herring stock subjected to a catastrophic event and fluctuating environmental conditions. Journal du Conseil, 43, 26-42. 15. Zheng, J. (1996). Herring stock-recruitment relationships and recruitment patterns in the North Atlantic and Northeast Pacific oceans. Fisheries Research, 26, 257-277. 6 South coast herring (depleted or rare species) within the PBGB LOMA. Temperature change Atlantic herring within the Newfoundland region are at the northern extent of their geographic range. Ideal conditions seldom exist and consequently strong recruitment is very sporadic. It has been shown (Winters et al., 1986) that when good survival of young herring (i.e., recruitment) occurred through the 1960's to 1980's, it was largely influenced by suitable environmental conditions, principally warm over-wintering water temperatures and high salinities prior to spawning. A global increase in air and sea temperature is predicted as a result of increased atmospheric concentrations of greenhouse gases, with Polar Regions most affected (IPCC, 2007). Winter temperatures in Northern Canada are expected to rise by 40% more than global averages. Within the PBGB LOMA, over the short term, this trend is less clear as increasing Arctic temperatures and associated ice melt may result in increased advection of cold fresh water by the Labrador Current. Such changes are difficult to predict, but may include localized cooling and greater inter-annual variability (UNEP & UNFCCC, 2002), although a general increase in temperature and reduction in salinity is expected throughout the water column (Frank et al., 1990). Surface waters (upper 30 metres) are heating up more rapidly than deeper waters, but temperature changes have also been detected at substantial depths (UNEP & UNFCCC, 2002). On the Grand Banks, the area of bottom covered by sub-zero water has decreased from >50% during the first half of the 1990s to near 15% during the past 3 years (Fisheries and Oceans Canada, 2007). Minor temperature changes in bottom water which normally undergo minimal natural variation may be more harmful than more substantial changes in surface waters. This temperature rise is not predicted to be linear, but will escalate over time. For the purposes of this assessment, following the precautionary principle, we will assume a maximum increase in water temperature of 0.3-0.4oC over the next ten years (Chafe & Power, 2002; Frank et al., 1990; Lily & Carscadden, 2002; Rose, 2005). Magnitude of Interaction Areal extent: Atlantic herring in division 3Ps are referred to as the South coast herring stock and they are likely found 12 months of the year within the LOMA (Scott & Scott, 1988). Most climate change stressors are considered to be constantly escalating stressors affecting the entire globe, and therefore areal extent will be 100% (for a score of 10). Score 10.0 Contact: Herring are a pelagic species which can be found throughout the upper water column. Spawning occurs in spring in inshore shallows, while fall spawning occurs in coastal or deeper waters. 1 Atlantic herring are demersal spawners, depositing their adhesive eggs on stable bottom substrates. Predicted change for surface waters is based on the maximum predicted rise, while the predicted change for deeper waters is based on the minimum predicted rise (Drinkwater, 2005) since deep waters are expected to heat less rapidly than surface waters (UNEP & UNFCCC, 2002). Since herring spawn is shallow coastal water and feed in surface waters, contact is likely high as these areas are expected to see the greatest fluctuations due to climate change. Score 8 Duration: The CP refers to the survival and recovery of South coast herring (depleted or rare species) within the PBGB LOMA. Herring spawn stocks spawn in the spring or in the fall and there is quite a bit of variability between spawning seasons and stocks with little evidence to explain the variations. Once hatched, juveniles herring are pelagic and would unlikely migrate out of the south coast region within the first year (Scott & Scott, 1988). Therefore based on this information herring would remain in the LOMA year round. The effects of temperature change are expected to occur throughout the year. Average annual duration = 100%. Score 10 Intensity Halpern et al. (2008) have developed maps showing the global intensity of several climate change stressors including changes in sea surface temperature (Halpern et al., 2008). These maps can be used to provide guidance in scoring the intensity of a stressor in relation to maximum (100%) intensity in a global context, in accordance with the scale provided below. Fig 1 below shows the potential for ecological change in response to sea surface temperature based on the frequency of temperature anomalies from 2000 to 2005, compared to 1985-1990, normalized by the standard deviation: Map colour Red Orange Yellow Light Blue Dark Blue Intensity 80-100% 60-80% 40-60% 20-40% 0-20% Figure 2. Potential for ecological change in response to Sea Surface Temperature (adapted from (Halpern et al., 2008) 2 Based on this information, south coast herring would be exposed to an intensity level between 40-60%, and we have chosen a moderate score. Score 6 Magnitude of Interaction: (10 x 8 x 10 x 6)/1000 = 4.8 Sensitivity Sensitivity of the CP to acute impacts: Changes in water temperature effects and influences growth rates and maturation of both juvenile and adult herring (Melvin et al., 2009; Wheeler et al., 2009; Winters et al., 1986). Atlantic herring are sensitive to changes in the marine environment, as temperature and salinity conditions is seen to have an affect on herring recruitment (Melvin et al., 2009; Winters et al., 1986). Analysis of annual variations in the growth of St. Mary's - Placentia Bay herring has shown that environmental temperatures were the main determinants of adult growth rates (Winters et al., 1986). Since the Newfoundland stocks of herring are at the species northerly limit, spring spawning herring experience the coldest temperatures and have the lowest growth rates (Winters et al., 1986) which would result in subsequently lower recruitment into the spawning stock. When adult growth rate is decreased, they could be of smaller stature and of lower fitness (from the reduced growth period), which could cause a decreased fecundity (Melvin et al., 2009; Scott & Scott, 1988; Wheeler et al., 2009; Winters et al., 1986) Based on this information the CP’s sensitivity to acute impacts is ranked high, but since the impacts may be negative or positive, we have selected a moderate score. Score 5 Sensitivity of the CP to chronic impacts: It has been suggested that herring stocks may migrate to more northerly regions with the warming of ocean temperatures (Melvin et al., 2009). Herring could establish north of southern Labrador in areas not previously occupied which could be clearly linked to the warming (Melvin et al., 2009). Since Herring stocks within the LOMA are at the northern edge of their range, long term impacts of temperature change are expected to be beneficial, so the anticipated harm is likely low (score 2) Atlantic herring are listed in the CP document as a ‘depleted and rare species’, and will therefore rank higher on this scale than other CPs because they are already in need of recovery (add one point). Score 3 3 Sensitivity of ecosystem to harmful impacts to the CP: Young and adult herring are important food for many other species, including many fishes, marine birds and marine mammals. In general herring are preyed upon by nearly all pelagic predators and are the base food for many of them. Herring eggs and larvae are subject to predation by a variety of bottom creatures including winter flounder, cod, haddock, red hake, sculpins, skates, and smelt (Scott & Scott, 1988). Herring are a high energy food source and play a key role in marine food webs, although with the decrease in herring stocks prior to the 1970’s, it is challenging to estimate the impact the Atlantic herring had on an ecosystem as a whole, although it is predicted to be great. Score 6 Sensitivity: (5 + 3 + 6)/3 = 4.7 Risk of Harm: MoI x S = 4.8 x 4.7= 22.6 4 Certainty Checklist Answer yes or no to all of the following questions. Record the number of NO’s to the 9 questions, and record certainty according to the scale provided below: 1 No’s = High certainty 2 - 3 No’s = Medium certainty No’s = Low certainty >4 Y/N N Is the score supported by a large body of information? Y Is the score supported by general expert agreement? N Is the interaction well understood, without major information gaps/sources of error? N Is the current level of understanding based on empirical data rather than models, anecdotal information or probable scenarios? Y Is the score supported by data which is specific to the region, (EBSA, LOMA, NW Atlantic)? Y Is the score supported by recent data or research (the last 10 years or less)? Y Is the score supported by long-term data sets (ten years or more) from multiple surveys (5 years or more)? Y Do you have a reasonable level of comfort in the scoring/conclusions? N Do you have a high level of confidence in the scoring/conclusions? Score: Low For interactions with Low certainty, underline the main factor(s) contributing to the uncertainty: Lack of comprehensive data Lack of expert agreement Predictions based of future scenarios which are difficult to predict Other (provide explanation) Suggest possible research to address uncertainty. 5 Reference List 1. Chafe, S. & Power, B. (2002). White Rose Go-Ahead - Shipyard Sold. VOCM Radio Newfoundland Ltd. [On-line]. Available: http://www.vocm.com 2. Drinkwater, K. F. (2005). The response of Atlantic cod (Gadus morhua) to future climate change. ICES Journal of Marine Science, 62, 1327-1337. 3. Fisheries and Oceans Canada (2007). 2006 State of the Ocean: Physical Oceanographic Conditions in the Newfoundland and Labrador Region (Rep. No. 2007/025). Canadian Science Advisory Secretariat Science Advisory Report. 4. Frank, K. T., Perry, R. I., & Drinkwater, K. F. (1990). Predicted Response of Northwest Atlantic Invertebrate and Fish Stocks to CO 2 -Induced Climate Change. Transactions of the American Fisheries Society, 119, 353-365. 5. Halpern, B. S., Walbridge, S., Selkoe, K. A., Kappel, C. V., Micheli, F., D'Agrosa, C. et al. (2008). A Global Map of Human Impact on Marine Ecosystems. Science, 319, 948-952. 6. IPCC (2007). A report of Working Group I of the Intergovernmental Panel on Climate Change: Summary for Policymakers Cambridge, United Kingdom and New York, NY, USA: Cambridge University Press. 7. Lily, G. R. & Carscadden, J. E. (2002). Predicting the future of marine fish and fisheries off Labrador and eastern Newfoundland under scenarios of climate change; information and thoughts for the Arctic Climate Impact Assessment (AICA) (Rep. No. 2002/111). Canadian Science Advisory Secretariat Research Document, Fisheries and Oceans Canada. 8. Melvin, G. D., Stephenson, R. L., & Power, M. J. (2009). Oscillating reproductive strategies of herring in the western Atlantic in response to changing environmental conditions. ICES Journal of Marine Science: Journal du Conseil, fsp173. 9. Rose, G. A. (2005). On distributional responses of North Atlantic fish to climate change. ICES Journal of Marine Science, 62, 1360-1374. 10. Scott, W. B. & Scott, M. G. (1988). Atlantic Fishes of Canada. Canadian Bulletin of Fisheries and Aquatic Sciences, 219. 11. UNEP & UNFCCC (2002). Climate Change Information Kit UNEP and UNFCCC. 12. Wheeler, J. P., Purchase, C. F., Macdonald, P. D. M., Fill, R., Jacks, L., Wang, H. et al. (2009). Temporal changes in maturation, mean length-at-age, and condition of spring-spawning Atlantic herring (Clupea harengus) in Newfoundland waters. ICES Journal of Marine Science: Journal du Conseil, fsp117. 6 13. Winters, G. H., Wheeler, J. P., & Dalley, E. L. (1986). Survival of a herring stock subjected to a catastrophic event and fluctuating environmental conditions. Journal du Conseil, 43, 26-42. 7 Summary Table: South coast herring (depleted or rare species) within the PBGB LOMA. Key Activity/Stressor a Temperature change 10 c d i MoI as cs es (a x c x d x i) 1000 8 10 6 4.8 S (as+cs+es) 3 5 3 6 4.7 Risk of Harm 22.6 Cumulative CP Score 22.6 Certainty Low