scholarly journals Does a spatiotemporal closure to fishing Chrysophrys auratus (Sparidae) spawning aggregations also protect individuals during migration?

2019 ◽  
Vol 76 (7) ◽  
pp. 1171-1185 ◽  
Author(s):  
B.M. Crisafulli ◽  
D.V. Fairclough ◽  
I.S. Keay ◽  
P. Lewis ◽  
J.R. How ◽  
...  
Keyword(s):  
Acoustic Telemetry ◽  
Migratory Fish ◽  
Current Management ◽  
Migration Timing ◽  
Spawning Aggregations ◽  
Biomass Assessment ◽  
Main Pathway ◽  
Migration Dynamics ◽  
Australian City ◽  
Spawning Biomass

Understanding migration dynamics of fishes that aggregate-spawn is critical if spatiotemporal closures to fishing are expected to protect them. Concern over fishing of Chrysophrys auratus spawning aggregations in embayments near a west Australian city led to an annual 4-month spatial fishing closure. However, the extent to which it protects fish migrating to and from aggregations is unclear. Acoustic telemetry demonstrated a bimodal pattern of entry to and departure from the main embayment via only one of several pathways. Among years, 33%–56% of fish occurred in the pathway prior to the closure, but most left before it ceased. Fish were detected within the closure in multiple but not always consecutive years. Variation in migration timing and aggregation philopatry may alter capture risk, but pre- and postspawning migratory fish are fished in the main pathway and adjacent reefs, which would presumably impact spawning aggregation biomass. Assessment of this would assist in understanding whether expansion of the closure’s spatial and temporal limits is necessary to ensure spawning biomass or whether current management is sufficient.

scholarly journals An investigation of the spawning behaviour of the chokka squid Loligo reynaudii and the potential effects of temperature using acoustic telemetry

2009 ◽  
Vol 67 (2) ◽  
pp. 231-243 ◽  
Author(s):  
Nicola J. Downey ◽  
Michael J. Roberts ◽  
Dan Baird
Keyword(s):  
Acoustic Telemetry ◽  
Environmental Variability ◽  
Spawning Site ◽  
Spawning Aggregations ◽  
Spawning Behaviour ◽  
Effects Of Temperature ◽  
Continuous Presence ◽  
Receiver Arrays ◽  
Spawning Sites

Abstract Downey, N. J., Roberts, M. J., and Baird, D. 2010. An investigation of the spawning behaviour of the chokka squid Loligo reynaudii and the potential effects of temperature using acoustic telemetry. – ICES Journal of Marine Science, 67: 231–243. Spawning aggregations of chokka squid are influenced by environmental conditions. Acoustic telemetry was used to monitor the behaviour of spawning squid in relation to environmental variability. During the November squid-fishery closed seasons of 2003–2006, hexagonal VR2 receiver arrays were moored on and around active spawning aggregations in Kromme Bay, South Africa. In all, 45 squid were tagged (V9P-6L-S256 transmitters) and released within these arrays. Three presence–absence behaviours were identified: (i) arrival on the spawning site at dawn and departure after dusk, (ii) continuous presence for a number of days, and (iii) presence interrupted by frequent but short periods of absence. Movement between spawning sites was both diurnal and nocturnal. Squid presence at the monitored sites increased after dawn and decreased towards and after dusk. Occasionally, a core aggregation of squid remained on the spawning sites at night. Temperature data at the sites indicated occasional upwelling, and although the role of temperature in the spawning process is not well understood, data suggest that it is linked to the continuation and or interruption of spawning after an aggregation has formed. The initial formation of spawning aggregations appears to be triggered by upwelling events.

Distribution of hoki (Macruronus novaezelandiae) eggs, larvae, and adults off Westland, New Zealand, and the design of an egg production survey to estimate hoki biomass

1998 ◽  
Vol 55 (7) ◽  
pp. 1682-1694 ◽  
Author(s):  
John R Zeldis ◽  
Rob C Murdoch ◽  
Patrick L Cordue ◽  
Mike J Page
Keyword(s):  
New Zealand ◽  
Egg Production ◽  
Abundance Estimate ◽  
Trawl Fishery ◽  
Spawning Aggregations ◽  
Biomass Estimate ◽  
Acoustic Surveys ◽  
Newly Hatched Larvae ◽  
Estimate Precision ◽  
Spawning Biomass

The winter spawning aggregations of hoki (Macruronus novaezelandiae) off the Westland coast, South Island, support New Zealand s largest trawl fishery. The distribution and abundance of hoki eggs, larvae, and adults from ichthyoplankton and acoustic surveys made during the period 1978-1993 were used to describe the location and timing of hoki spawning off Westland. Hoki spawned primarily in south Westland, around Hokitika Canyon, and south along the outer shelf and slope to Cook Canyon, although spawning biomass appeared to increase in north Westland later in the season. Older stage hoki larvae occurred shoreward of eggs and newly hatched larvae, suggesting onshore advection. The data were used to designate spatial and temporal egg sampling strata that significantly increased egg abundance estimate precision. The egg data were used to estimate annual egg production and, combined with data on fecundity and recruited proportion spawning, to estimate virgin biomass. The historical biomass estimate (1.48 million tonnes, CV = 29.4%) was probably biased down because the plankton tows were too shallow. It appears that a future egg production survey, using appropriate plankton sampling depths, could provide a biomass estimate of Westland spawning hoki sufficiently accurate and precise for management purposes.

Estimating the dynamics of spawning aggregations using biological and fisheries data

2016 ◽  
Vol 67 (3) ◽  
pp. 342 ◽  
Author(s):  
André E. Punt ◽  
David C. Smith ◽  
Malcolm Haddon ◽  
Sarah Russell ◽  
Geoffrey N. Tuck ◽  
...  
Keyword(s):  
Stock Assessment ◽  
Spawning Season ◽  
Turnover Rates ◽  
Spawning Grounds ◽  
Arrival Times ◽  
Spawning Aggregations ◽  
Average Proportion ◽  
Acoustic Surveys ◽  
Males And Females ◽  
Spawning Biomass

Acoustic surveys can provide accurate estimates of biomass at a particular location at a point in time, but provide a negatively biased estimate of the total spawning population unless the proportion of fish that are unavailable to the survey is accounted for. Changes to the ages and maturity stages of fish caught during the spawning season is evidence for turnover of fish during spawning and, along with information on relative abundance, provides a basis for estimating turnover rates. A model is therefore developed that tracks the numbers of males and females by age as they arrive on the spawning grounds, initiate spawning, complete spawning and leave the spawning grounds. This model can be used to determine the proportion of the spawning biomass on the spawning grounds over the spawning season. It is applied to data for blue grenadier, Macruronus novaezelandiae, off western Tasmania, Australia. The results can be used to estimate the average proportion of the population available to an acoustic survey, although this estimate is not likely to be very precise, owing to the high between-year variation in arrival times. However, the model provides a quantitative estimate of turnover rate that was previously not available, and is a rigorous basis for estimating turnover for stock assessment.

scholarly journals Adfluvial salmonids have engineering but not fertilization impacts in tributaries of a central Utah reservoir

2018 ◽  
Vol 75 (3) ◽  
pp. 389-401 ◽  
Author(s):  
Kit Wheeler ◽  
Scott W. Miller ◽  
Todd A. Crowl
Keyword(s):  
Model Comparison ◽  
Cutthroat Trout ◽  
Migratory Fish ◽  
Oncorhynchus Clarkii ◽  
Ecosystem Properties ◽  
Migration Timing ◽  
Comparison Approach ◽  
Fertilization Effects ◽  
Ecosystem Drivers ◽  
Bonneville Cutthroat Trout

Migratory fishes can affect tributary ecosystem properties given their potential to introduce nutrients (fertilize) and physically modify habitat (engineer) during spawning. Nonetheless, migrant effects are frequently context-dependent, and it is useful to understand their strength relative to other potential ecosystem drivers. We examined whether tributary ecosystem properties varied in response to migrations of two adfluvial salmonids, taking advantage of differences in migration timing and reproductive strategy between species, as well as hydrogeomorphic differences between a pair of tributaries. For analyses, we used a model comparison approach to evaluate migrant effects relative to other possible drivers. We observed that Bonneville cutthroat trout (Oncorhynchus clarkii utah) engineered benthic chlorophyll a in redds, with reduction (51% ± 16% decrease) generally occurring during migrations. Contrary to expectations, migrant fertilization effects were not pronounced even in the more retentive tributary during migration by species (kokanee, Oncorhynchus nerka) that exhibited high postspawning mortality. Based on multimodel comparisons, isolated migrant effects were not the primary influence on measured ecosystem properties. Our findings underscore the need to consider different biotic and abiotic conditions that can mediate migratory fish effects.

scholarly journals Upstream and downstream migration speed of Prochilodus costatus (Characiformes: Prochilodontidae) in upper São Francisco basin, Brazil

2019 ◽  
Vol 17 (2) ◽  
Author(s):  
João de Magalhães Lopes ◽  
Carlos Bernardo Mascarenhas Alves ◽  
Alexandre Peressin ◽  
Paulo Santos Pompeu
Keyword(s):  
Swimming Performance ◽  
Upstream Migration ◽  
Migration Speed ◽  
Migratory Fish ◽  
Neotropical Fishes ◽  
Sao Francisco River ◽  
São Francisco River ◽  
Migration Dynamics ◽  
Post Spawning ◽  
And Migration

ABSTRACT Details of migration dynamics of Neotropical fishes are poorly understood. This study aimed to examine upstream (spawning) and downstream (post-spawning) migration speeds, of curimatá-pioa (Prochilodus costatus) in the São Francisco River basin, southeast Brazil. Most upstream movements were recorded in October and November, in two well-defined migration windows, and downstream movements were frequent from December to March. Fish migrated upstream at an average migration speed of 34.4 km day-1 and no significant differences were detected in their speed between sexes and migration window they selected to migrate. No relationship was detected between upstream migration speed and biometric measures of tagged individuals. Upstream migrations speeds were significantly higher for fish that swam longer prior to reach telemetry stations in the same season, indicating that swimming performance may take some time to achieve its peak in upstream migration. Fish migrated downstream at an average migration speed of 97.7 km day-1, what is close to passive swimming in São Francisco River, and no significant differences in speed were detected between sexes or capture sites. The migration speeds measured here are the highest ever recorded for the genus Prochilodus and are among the highest reported for Neotropical migratory fish.

scholarly journals Extent of predation bias present in migration survival and timing of Atlantic salmon smolt (Salmo salar) as suggested by a novel acoustic tag

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Jason Daniels ◽  
Stephen Sutton ◽  
Dale Webber ◽  
Jonathan Carr
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Acoustic Telemetry ◽  
Lower Estuary ◽  
Ph Change ◽  
Apparent Survival ◽  
Migration Timing ◽  
Acoustic Tags ◽  
Receiver Arrays ◽  
Salmon Smolt

Abstract Background Acoustic telemetry is increasingly being used as a tool to measure survival, migration timing and behaviour of fish. Tagged fish may fall prey to other animals with the tag continuing to be detected whilst it remains in the gastrointestinal tract of the predator. Failure to identify post-predation detections introduces “predation bias” into the data. We employed a new predator tag technology in the first known field trial to understand the extent these tags could reduce predation bias in Atlantic salmon (Salmo salar L.) smolt migration through a 65-km zone beginning in freshwater and extending through an estuary. These tags signal predation by detecting a pH change in the predators’ gut during digestion of a tagged prey. We quantified survival and timing bias by comparing measurements from non- and post-predated detections of tagged individuals’ to only those detections where predation was not signalled. Results Of the 50 fish tagged, 41 were detected with 24 of these signalling as predated. Predation bias was greatest in the upper estuary and decreased towards the bay. Survival bias peaked at 11.6% at river km 54. Minimum and maximum migration time were both biased long and were 16% and 4% greater than bias corrected timing at river km 66 and 54, respectively. After correcting for bias, the apparent survival from release through freshwater and estuary was 19% and minimum and maximum migration timing was 6.6 and 7.0 days, respectively. Conclusions Using this tag, we identified a high proportion of predation events that may have otherwise gone unnoticed using conventional acoustic tags. Estimated survival presented the greatest predation bias in the upper estuary which gradually declined to nearly no apparent bias in the lower estuary as predated tags failed through time to be detected. This is most likely due to tag expulsion from the predator between or upstream of receiver arrays. Whilst we have demonstrated that predation can bias telemetry results, it appears to be rather short-lived given the apparent retention times of these tags within the predators introducing the bias.

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