Incorporating spatial and seasonal dimensions in a stock reduction analysis for lower Fraser River white sturgeon (Acipenser transmontanus)

2012 ◽  
Vol 69 (10) ◽  
pp. 1674-1697 ◽  
Author(s):  
Rebecca E. Whitlock ◽  
Murdoch K. McAllister
Keyword(s):  
Posterior Probability ◽  
Mortality Rates ◽  
White Sturgeon ◽  
Acipenser Transmontanus ◽  
Current Status ◽  
Fraser River ◽  
Fishing Mortality ◽  
Abundance Estimates ◽  
Spawning Stock ◽  
Stock Abundance

We applied a spatially and seasonally structured stock reduction analysis (SRA) model to white sturgeon ( Acipenser transmontanus ) in the lower Fraser River, British Columbia, to estimate trends in abundance since the 1800s and evaluate the current status of the population. We used a sequential Bayesian state–space estimation approach to incorporate prior information from other analyses and evaluate the updating of prior knowledge within the SRA model. The estimated ratio of the abundance of spawning fish in 2004 to relative to unfished conditions was slightly higher than estimates from other studies; on average, 27% of the posterior probability was associated with a 2004 spawning stock abundance of 50% or less of the unfished abundance. Estimates of the current abundance of fish vulnerable to the lower Fraser River recreational fishery were higher than those obtained in other recent SRAs that ignored spatial structure. We also performed the analysis using a spatially aggregated version of the SRA model and obtained lower estimates of unfished biomass and depletion and higher estimates of fishing mortality rates compared with the spatially structured model. We evaluated two structural hypotheses about age-specific vulnerabilities in the historical commercial fishery; assumed vulnerabilities had a marked impact on estimated fishing mortality rates.

Acute Toxicity Testing with Juvenile White Sturgeon (Acipenser transmontanus)

1998 ◽  
Vol 33 (1) ◽  
pp. 95-110 ◽  
Author(s):  
W.R. Bennett ◽  
A.P. Farrell
Keyword(s):  
Acute Toxicity ◽  
Swimming Performance ◽  
Juvenile Fish ◽  
Toxicity Testing ◽  
White Sturgeon ◽  
Acipenser Transmontanus ◽  
Toxicity Tests ◽  
Fraser River ◽  
Acute Toxicity Tests ◽  
Acute Toxicity Testing

Abstract The primary goal of this study was to investigate the possibility of using early life stages of white sturgeon (Acipenser transmontanus) (eggs, larvae and fry) as a species relevant to the Fraser River, B.C., for the acute and sublethal toxico-logical testing of forest industry effluents. Here we report the first successful acute toxicity tests for 8-day-old larvae and 42-day-old fry exposed to several chemicals known to be released into the Fraser River (i.e., 6 monochlorovanillin [6 MVAN], 4,5 dichloroguaiacol [4,5 DCG], 4,5 dichlorocatechol [4,5 DCAT], pentachlorophenol [PCP], and didecyldimethylammonium chloride [DDAC]). In most cases, white sturgeon fry were at the lower end of the range for acute toxicity values for chlorinated phenolic compounds, when compared with other juvenile fish species, and they were extremely sensitive to DDAC. The larval stage was usually more sensitive than the fry stage. Acute toxicity tests with fertilized eggs were unsuccessful. A postexposure growth study was inconclusive because neither control nor toxicant-exposed larvae and fry withstood the additional handling used for measuring body mass. At 62-days-old, fry were more tolerant of handling. This allowed measurement of their swimming performance. Although we have concerns about the reliability of using larvae for acute toxicity testing at this time, 60-day-old white sturgeon fry would appear to be both a sensitive and relevant species for assessing environmental impacts relevant to the Fraser River.

scholarly journals North Sea cod recovery?

2006 ◽  
Vol 63 (6) ◽  
pp. 961-968 ◽  
Author(s):  
Joe Horwood ◽  
Carl O'Brien ◽  
Chris Darby
Keyword(s):  
North Sea ◽  
Gadus Morhua ◽  
Mortality Rates ◽  
Fishing Effort ◽  
Current Status ◽  
Fishing Mortality ◽  
Commercial Fish ◽  
Fish Stocks ◽  
Stock Assessments ◽  
Low Levels

AbstractRecovery of depleted marine, demersal, commercial fish stocks has proved elusive worldwide. As yet, just a few shared or highly migratory stocks have been restored. Here we review the current status of the depleted North Sea cod (Gadus morhua), the scientific advice to managers, and the recovery measures in place. Monitoring the progress of North Sea cod recovery is now hampered by considerable uncertainties in stock assessments associated with low stock size, variable survey indices, and inaccurate catch data. In addition, questions arise as to whether recovery targets are achievable in a changing natural environment. We show that current targets are achievable with fishing mortality rates that are compatible with international agreements even if recruitment levels remain at the current low levels. Furthermore, recent collations of data on international fishing effort have allowed estimation of the cuts in fishing mortality achieved by restrictions on North Sea effort. By the beginning of 2005, these restrictions are estimated to have reduced fishing mortality rates by about 37%. This is insufficient to ensure recovery of North Sea cod within the next decade.

CONTAMINANTS IN WHITE STURGEON (ACIPENSER TRANSMONTANUS) FROM THE UPPER FRASER RIVER, BRITISH COLUMBIA, CANADA

1997 ◽  
Vol 16 (3) ◽  
pp. 479 ◽  
Author(s):  
Donald D. MacDonald ◽  
Michael G. Ikonomou ◽  
Anna-Lea Rantalaine ◽  
I. Hal Rogers ◽  
David Sutherland ◽  
...  
Keyword(s):  
British Columbia ◽  
White Sturgeon ◽  
Acipenser Transmontanus ◽  
Fraser River

Concentrations of strontium in the pectoral fin rays of the white sturgeon (Acipenser transmontanus) by laser ablation sampling - inductively coupled plasma - mass spectrometry as an indicator of marine migrations

1999 ◽  
Vol 56 (11) ◽  
pp. 1981-1990 ◽  
Author(s):  
Geoff Veinott ◽  
Tom Northcote ◽  
Marvin Rosenau ◽  
R Douglas Evans
Keyword(s):  
Mass Spectrometry ◽  
Laser Ablation ◽  
Inductively Coupled Plasma ◽  
White Sturgeon ◽  
Acipenser Transmontanus ◽  
Fraser River ◽  
Inductively Coupled ◽  
Fin Ray ◽  
Fin Rays ◽  
Plasma Mass Spectrometry

Laser ablation sampling - inductively coupled plasma - mass spectrometry (LAS-ICP-MS) was an effective technique for the comparison of relative Sr concentrations in the opaque growth zones (annuli) in the fin rays of white sturgeon (Acipenser transmontanus). Three of 29 Fraser River white sturgeon (10.3% of the sample) showed significantly higher Sr fin ray concentrations in at least one annulus compared with the remainder of the fin ray, and this was interpreted as evidence of marine migrations. Eleven other individual fish had significantly higher mean Sr concentrations in their first 15 annuli compared with annuli 16-30 but lower than the concentrations of the three putative diadromous fish, and this was interpreted as evidence of time spent in the estuary. Eight Fraser River fish greater than 15 years old showed no significant increase in fin ray Sr concentations in the first 15 annuli, and Sr concentrations remained below 350 ppm throughout their lives. These individuals were considered likely to have spent most of their lives in a freshwater environment. Based on the evidence in this study, it is probable that the majority of white sturgeon in the lower Fraser River are not diadromous, but many spend extended periods of time in the Fraser River estuary as juveniles.

Contaminants in white sturgeon (Acipenser transmontanus) from the upper Fraser River, British Columbia, Canada

1997 ◽  
Vol 16 (3) ◽  
pp. 479-490 ◽  
Author(s):  
Donald D. MacDonald ◽  
Michael G. Ikonomou ◽  
Anna-Lea Rantalaine ◽  
I. Hal Rogers ◽  
David Sutherland ◽  
...  
Keyword(s):  
British Columbia ◽  
White Sturgeon ◽  
Acipenser Transmontanus ◽  
Fraser River

Parasites of White Sturgeon, Acipenser transmontanus, from the Fraser River, British Columbia

1986 ◽  
Vol 72 (5) ◽  
pp. 794 ◽  
Author(s):  
L. Margolis ◽  
T. E. McDonald
Keyword(s):  
British Columbia ◽  
White Sturgeon ◽  
Acipenser Transmontanus ◽  
Fraser River

Juvenile white sturgeon (Acipenser transmontanus) habitat and distribution in the Lower Fraser River, downstream of Hope, BC, Canada

2005 ◽  
Vol 21 (5) ◽  
pp. 375-380 ◽  
Author(s):  
W. R. Bennett ◽  
G. Edmondson ◽  
E. D. Lane ◽  
J. Morgan
Keyword(s):  
White Sturgeon ◽  
Acipenser Transmontanus ◽  
Fraser River

scholarly journals An evaluation of multi-annual management strategies for ICES roundfish stocks

2006 ◽  
Vol 63 (1) ◽  
pp. 12-24 ◽  
Author(s):  
L.T. Kell ◽  
G.M. Pilling ◽  
G.P. Kirkwood ◽  
M.A. Pastoors ◽  
B. Mesnil ◽  
...  
Keyword(s):  
Current System ◽  
Management Strategies ◽  
Integrated Modelling ◽  
Current Status ◽  
Scientific Management ◽  
Fishing Mortality ◽  
Modelling Framework ◽  
Management Objectives ◽  
Spawning Stock ◽  
High Level

Abstract Current scientific management objectives for ICES roundfish stocks are to ensure conservation of the biological resource and do not explicitly consider economic or social objectives. For example, there are currently no objectives to maximize the sustainable yield or to reduce variability in total allowable catches (TACs). This is despite the fact that the current system can result in wide annual fluctuations in TAC, limiting the ability of the fishing industry to plan for the future. Therefore, this study evaluated management strategies that stabilized catches by setting bounds on the interannual variability in TACs. An integrated modelling framework was used, which simulated both the real and observed systems and the interactions between system components. This allowed the evaluation of candidate management strategies with respect to the intrinsic properties of the systems, as well as our ability to observe, monitor, assess, and control them. Strategies were evaluated in terms of risk (measured as the probability of spawning-stock biomass falling below a biomass threshold for the stock) and cumulative yield. In general, bounds on interannual TAC change of 10% and 20% affected the ability to achieve management targets, although the outcome of applying TAC bounds could not have been pre-judged because results were highly dependent on the specific biology of the stock, current status, and the interaction with assessment and management. For example, for North Sea haddock, management became less responsive to fluctuations resulting from large recruitment events. Simulated target fishing mortality levels were rarely achieved, regardless of the TAC bound applied, and actual fishing mortality rates oscillated around the target. In the longer term, more restrictive bounds resulted in oscillations of greater amplitude and wavelength in yield and SSB. Bounds had less effect when a stock was close to the biomass corresponding to the target F. Risk for stocks that are declining or currently at low abundance may be greater, because if bounds restrict the extent to which TACs can be reduced each year, they could lead to collapse of the stock and the loss of all future revenue. However, for a recovered stock or one at high abundance, the loss of yield as a result of bounds would be smaller than that caused by the total collapse of the fishery. At low stock size or if the stock was declining, catches should be changed more rapidly than when the stock was increasing or at a high level, especially high stock sizes acting as an insurance against uncertainty. Therefore, rebuilding strategies, and strategies aimed at maintaining the stock above prescribed limits, should be considered separately.

Influence of Pleistocene Glaciations and Human Intervention upon Mitochondrial DNA Diversity in White Sturgeon (Acipenser transmontanus) Populations

1992 ◽  
Vol 49 (2) ◽  
pp. 358-367 ◽  
Author(s):  
James R. Brown ◽  
Andrew T. Beckenbach ◽  
Michael J. Smith
Keyword(s):  
Mitochondrial Dna ◽  
Columbia River ◽  
Habitat Destruction ◽  
White Sturgeon ◽  
Acipenser Transmontanus ◽  
Northwest Pacific ◽  
Fraser River ◽  
Animal Populations ◽  
Mtdna Diversity ◽  
The Last Glacial

The influence of recent genetic bottlenecks on two Northwest Pacific populations of white sturgeon (Acipenser transmontanus) was studied using restriction enzyme site differences in mitochondrial DNA (mtDNA). A total of 10 mtDNA genotypes were detected in 178 sturgeon from the Columbia and Fraser rivers. Nearly 61% of individuals from both rivers had a common genotype. However, one genotype was found only in the Fraser River. Geographical substructuring was not evident in the phylogenetic analysis. The Columbia River, a Pleistocene refugium, is suggested as the source of founders for the Fraser River following the last glacial recession, about 10 000–12 000 yr ago. MtDNA genotypic frequencies were significantly different between the rivers. Estimates of mtDNA (h) and nucleotide (π) diversity were consistently higher for the recently colonized Fraser River compared with the Columbia River refugium. This condition is the reverse of all known studies of mtDNA diversity between refugium and colonized animal populations. Recent overexploitation and habitat destruction are suggested as a severe genetic bottleneck that has reduced mtDNA diversity in Columbia River sturgeon.

Hierarchical patterns of population structure in the endangered Fraser River white sturgeon (Acipenser transmontanus) and implications for conservation

2012 ◽  
Vol 69 (12) ◽  
pp. 1968-1980 ◽  
Author(s):  
Andrea Drauch Schreier ◽  
Brian Mahardja ◽  
Bernie May
Keyword(s):  
Population Structure ◽  
Clustering Algorithm ◽  
River System ◽  
White Sturgeon ◽  
Population Substructure ◽  
Acipenser Transmontanus ◽  
Fraser River ◽  
Population Genetic Analysis ◽  
Management Units ◽  
Genetic Clustering

The Fraser River system consists of five white sturgeon (Acipenser transmontanus) management units, two of which are listed as endangered populations under Canada’s Species at Risk Act. The delineation of these management units was based primarily on population genetic analysis with samples parsed by collection location. We used polysomic microsatellite markers to examine population structure in the Fraser River system with samples parsed by collection location and with a genetic clustering algorithm. Strong levels of genetic divergence were revealed above and below Hells Gate, a narrowing of the Fraser canyon further obstructed by a rockslide in 1913. Additional analyses revealed population substructure on the Fraser River above Hells Gate. The Middle Fraser River (SG-3) and Nechako River were found to be distinct populations, while the Upper Fraser River, although currently listed as an endangered population, represented a mixing area for white sturgeon originating from SG-3 and Nechako. Differences between these results and previous genetic investigations may be attributed to the detection of population mixing when genetic clustering is used to infer population structure.

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