Abstract:Meta-analyses of field studies have shown that biomass, density, species richness, and size of organisms protected by no-take marine reserves generally increase over time. The magnitude and timing of changes in these response variables, however, vary greatly and depend upon the taxonomic groups protected, size and type of reserve, oceanographic regime, and time since the reserve was implemented. We conducted collaborative, fishery-independent surveys of fishes for seven years in and near newly created marine p… Show more
“…To put that amount in perspective, the San Francisco Bay covers ∼1,100 km 2 , drains 40% of the state of California (26,27), and receives an estimated annual load of 8.0 kg MeHg from external sources such as rivers and point source discharges (25). Conversely, the Año Nuevo State Marine Conservation Area covers only 26.4 km 2 (28), indicating that the magnitude of annual inputs from pinniped colonization constitutes a relevant, previously unaccounted for, source of MeHg to that marine reserve.…”
Methylmercury (MeHg) is a potent neurotoxin that is biomagnified approximately 1-10 million-fold in aquatic carnivores such as the Northern elephant seal (Mirounga angustirostris), whose excreta and molted pelage, in turn, constitute a source of environmental MeHg contamination at the base of marine food chains. The potential for this top-down contamination is greatest in coastal areas with productive marine ecosystems that provide ideal habitats for large marine mammal colonies that can number in the thousands. This recycling of MeHg was evidenced by comparing total mercury (HgT) and MeHg concentrations in seawater, and HgT in molted pelage of M. angustirostris, at the Año Nuevo State Reserve pinniped rookery with concentrations at neighboring coastal sites in Central California. Seawater MeHg concentrations around the rookery (average = 2.5 pM) were markedly higher than those at the comparison coastal sites (average = 0.30 pM), and were as high as 9.5 pM during the M. angustirostris molting season. As a consequence, excreta and molts from this marine mammal colony, and presumably other marine predator populations, constitute a major source of MeHg at the base of the local marine food chain. mercury | biogeochemistry | marine mammals | biomagnification | environmental toxicology
“…To put that amount in perspective, the San Francisco Bay covers ∼1,100 km 2 , drains 40% of the state of California (26,27), and receives an estimated annual load of 8.0 kg MeHg from external sources such as rivers and point source discharges (25). Conversely, the Año Nuevo State Marine Conservation Area covers only 26.4 km 2 (28), indicating that the magnitude of annual inputs from pinniped colonization constitutes a relevant, previously unaccounted for, source of MeHg to that marine reserve.…”
Methylmercury (MeHg) is a potent neurotoxin that is biomagnified approximately 1-10 million-fold in aquatic carnivores such as the Northern elephant seal (Mirounga angustirostris), whose excreta and molted pelage, in turn, constitute a source of environmental MeHg contamination at the base of marine food chains. The potential for this top-down contamination is greatest in coastal areas with productive marine ecosystems that provide ideal habitats for large marine mammal colonies that can number in the thousands. This recycling of MeHg was evidenced by comparing total mercury (HgT) and MeHg concentrations in seawater, and HgT in molted pelage of M. angustirostris, at the Año Nuevo State Reserve pinniped rookery with concentrations at neighboring coastal sites in Central California. Seawater MeHg concentrations around the rookery (average = 2.5 pM) were markedly higher than those at the comparison coastal sites (average = 0.30 pM), and were as high as 9.5 pM during the M. angustirostris molting season. As a consequence, excreta and molts from this marine mammal colony, and presumably other marine predator populations, constitute a major source of MeHg at the base of the local marine food chain. mercury | biogeochemistry | marine mammals | biomagnification | environmental toxicology
“…The much longer generation time for these species as well as the sporadic recruitment success of rockfish, implies that it will take longer than 3-7 years for reserve effects to develop as a result of increased growth and reproductive output of these species in RCAs. Similarly, Starr et al (2015) found strong reserve effects in an MPA that had been closed since 1973 but not in newer reserves in California that were sampled within the first 7 years of protection. They projected that MPAs in Central California may take 20 years or more to show significant changes in response variables (Starr et al, 2015).…”
Section: Discussionmentioning
confidence: 94%
“…Similarly, Starr et al (2015) found strong reserve effects in an MPA that had been closed since 1973 but not in newer reserves in California that were sampled within the first 7 years of protection. They projected that MPAs in Central California may take 20 years or more to show significant changes in response variables (Starr et al, 2015). Most rockfishes distributed along the continental slope did not show a greater proportion of large fish in closed areas of a large RCA in the US, unlike other species with shorter lifespans (Keller et al, 2014).…”
Section: Discussionmentioning
confidence: 94%
“…In order to improve the assessment of marine reserves, Claudet and Guidetti (2010) recommend that the actual fishing pressure outside of an MPA be quantified, rather than assumed, when effectiveness is assessed relative to external controls. Other management measures coincident with the creation of conservation areas complicates the evaluation of RCAs (Keller et al, 2014;Starr et al, 2015). In addition to establishing RCAs, DFO also greatly reduced the directed catch (Total Allowable Catch, TAC) for inshore rockfishes.…”
a b s t r a c tBetween 2004 and 2007, Fisheries and Oceans Canada undertook a management action to conserve overfished populations of Inshore Rockfishes by designating 164 Rockfish Conservation Areas (RCAs) closed to most recreational and commercial fishing. However, no research has yet assessed the effectiveness of the RCA network at promoting groundfish population recoveries. We surveyed the fish communities of 35 RCAs and adjacent unprotected areas in southern British Columbia using a remotely operated vehicle (ROV) between 2009 and 2011. We investigated the effect of protection and habitat on fish densities for six species or species groups (Quillback, Yelloweye, Greenstriped Rockfish, Kelp Greenling, Lingcod and all Inshore Rockfish combined) on transects inside and outside of RCAs. Habitat features such as percent rocky substrates and depth influenced fish density while reserve status did not. Next, we calculated habitat-based average densities and used the mean log response ratio (RR) of the density inside to outside of RCAs to determine if the amount of fishing outside the RCA, previous fishing history, the age, area or perimeter to area ratio influenced population recovery. Few positive reserve effects were apparent for any species/group. No clear patterns of RR with age were found for the RCAs, which ranged from 3 to 7 years old at the time of sampling (mean = 4.6). In addition, the intensity of fishing, size, and perimeter-to-area ratio failed to explain RR for most species. There were also no differences in size structure (length) of fish between RCAs and unprotected areas. The results give little indication that demersal fish populations have recovered inside the RCA system. Ongoing monitoring is essential to assess population recovery over time and evaluate the RCAs in terms of criteria such as habitat quality, habitat isolation and the level of compliance in order to enhance their effectiveness.Crown
“…For example, hook-and-line gear is used to sample rocky reefs that are home to many commercially and recreationally important species, as trawl gear would snag in these complex, hard-bottom habitats. Fishery-independent hook-and-line surveys (hereafter "hook and line" refers to pole-and-line gear specifically) have expanded in recent years in the nearshore waters of the northeastern Pacific Ocean both to assess reef fish abundance (Wendt and Starr 2009;Harms et al 2010) and to monitor marine reserve performance (Haggarty and King 2006;Yochum et al 2011;Huntington et al 2014;Starr et al 2015). The numbers of marine reserves are growing in both California, where 124 marine managed areas were implemented between 2007 and 2013 (Kirlin et al 2013), and Oregon, where 13 marine managed areas were implemented between 2012 and 2016.…”
Fishery-independent hook-and-line surveys are currently being used to assess marine reserve performance in California and Oregon using a regionally standardized approach. Catch compositions generated from these hookand-line surveys (pole-and-line gear) at Oregon's southernmost marine reserve were compared with local commercial landing data. Several species present in the commercial catch were undersampled in the marine reserve hook-and-line dataset, including China Rockfish Sebastes nebulosus, Vermilion Rockfish S. miniatus, Quillback Rockfish S. maliger, Copper Rockfish S. caurinus, and Cabezon Scorpaenichthys marmoratus. We conducted a gear selectivity study to explore whether modified commercial long-lining gear could supplement current hook-and-line efforts. Both gear types were fished simultaneously from a single vessel inside and outside of the reserve. Species composition, catch rate, size distribution, and fish condition between the two gear types were compared. Catch composition differed significantly between longline and hook-and-line gear. Catch rates of nearshore rocky reef fish species were higher for longline than hook-and-line gear for all but two species. Importantly, higher catch rates were significant for three of the species of interest (Cabezon, Vermilion Rockfish, and Copper Rockfish). For four different species, larger individuals were caught on the longline compared with the hook-and-line gear. Incidence of predation and mortality were higher with long-lining but limited to three species groups: Black Rockfish S. melanops, Blue Rockfish S. mystinus and Deacon Rockfish S. diaconus complex, and Canary Rockfish S. pinniger. Symptoms of barotrauma were higher with hook-and-line gear. We demonstrated that longline gear can be used to catch and release species targeted by the local fishery and used simultaneously with hook-and-line gear from a single vessel to broaden both the species and the size ranges sampled. These results underscore the need to consider regionally standardized long-term monitoring approaches in conjunction with locally tailored efforts to generate data for detecting marine reserve effects at both local and regional scales.Fishery-independent data-collected independently from fisheries landings and logbooks-are recognized as important for improving fishery stock assessments (Harms et al. 2010), monitoring for temporal changes in trophic structure (Shackell et al. 2010), and evaluating the performance of spatial fishing closures (Yoklavich et al. 2007). Different sampling methods have been used to generate fishery-independent data, including nonextractive visual surveys (Watson et al. 2005) and extractive surveys using a variety of fishing gear. Extractive surveys are particularly useful in the nearshore waters of the
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