Age determination, validation, and growth of blue cod<i>Parapercis colias</i>, in Foveaux Strait, New Zealand

Carbines, Glen

doi:10.1080/00288330.2004.9517231

Cited by 11 publications

(6 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Monitoring the density of large predatory reef fish can be an excellent indicator of the effect of protection because this index usually increases rapidly after establishment of an MR or MPA (Russ and Alcala, 1996;Davidson, 1997;Babcock et al, J a n -9 8 M a r -9 8 M a y -9 8 J u l-9 8 S e p -9 8 N o v -9 8 J a n -9 9 M a r -9 9 M a y -9 9 J u l-9 9 S e p -9 9 N o v -9 9 J a n - (Cole et al, 2001;Davidson, 2001;Carbines, 2004). The present sampling effort needs to be increased 3.5-fold to permit the detection of change in abundance of this species.…”

Section: Ecological Changes Arising From Marine Reserve Statusmentioning

confidence: 98%

A baseline biological survey of the proposed Taputeranga Marine Reserve (Wellington, New Zealand): spatial and temporal variability along a natural environmental gradient

Pande

Gardner

2008

Aquatic Conservation

View full text Add to dashboard Cite

ABSTRACT1. Four macroalgal, four macroinvertebrate and eight fish species were surveyed at eight sites (three inside, five outside the proposed reserve) over three years before the establishment of the Taputeranga Marine Reserve (MR) on Cook Strait (Wellington, New Zealand). This baseline data set was used to estimate temporal and spatial variability in size and abundance of these taxa, and will be used to quantify taxon-specific changes in size and abundance once the MR is established.2. Statistically significant differences in size and/or abundance were observed for many taxa among the sites. These differences are consistent with the existence of a natural environmental gradient from the west (entrance to Cook Strait) to the east (Wellington Harbour). This gradient highlights the importance of conducting a prereserve baseline survey at multiple sites and over multiple years to better understand the conservation or fisheries benefits that MRs are expected to deliver.3. Two macroalgal, one macroinvertebrate, and six fish species showed statistically significant seasonal variation in abundance. Subsequent multi-taxa monitoring needs to include a seasonal component to capture this natural variability.4. This multi-site and multi-year data set represents one of the most comprehensive and robust baseline data sets available anywhere in the world. It will be used to quantify the ecological changes associated with a newly established full no-take marine reserve. Ongoing monitoring will enhance understanding of the sizes and abundances of key taxa, allow a detailed determination of the conservation effects of reserve establishment, and inform management decisions for Wellington's south coast.

show abstract

Section: Ecological Changes Arising From Marine Reserve Statusmentioning

confidence: 98%

A baseline biological survey of the proposed Taputeranga Marine Reserve (Wellington, New Zealand): spatial and temporal variability along a natural environmental gradient

Pande

Gardner

2008

Aquatic Conservation

View full text Add to dashboard Cite

show abstract

“…No fish were sampled from the youngest age classes (B3 yrs) so t 0 was set to 0 for all models. As blue cod are protogynous hermaphrodites (Mutch 1983;Carbines 2004), growth was modelled separately for males and females.…”

Section: Modelling Of Growthmentioning

confidence: 99%

Trophic ecology drives spatial variability in growth among subpopulations of an exploited temperate reef fish

Beer

Wing

2013

New Zealand Journal of Marine and Freshwater Research

View full text Add to dashboard Cite

Blue cod (Parapercis colias) support important fisheries around New Zealand, but limited mixing over small spatial scales renders subpopulations vulnerable to depletion and highlights the importance of resolving fine-scale population structure. Fiordland represents a rare opportunity to achieve this in a relatively pristine environment and intact ecosystem. Between 2000 and 2004, spatial population structure in three fjords was used to test how spatial variability in growth between inner and outer fjord subpopulations can be statistically explained by diet, demography and site-specific factors. Sex ratios and size distributions vary between habitats, with a female bias and a higher frequency of individuals in the larger size classes within the inner fjords. Stomach content analysis shows that in the inner fjords the diet of blue cod includes a diverse array of benthic species while in the outer fjords P. colias is able to utilise a less diverse array of pelagic prey that may be of a higher nutritional quality. Stable isotope analysis reveals that in two of the three outer fjord habitat sites the Laminarian Ecklonia radiata accounts for a large component of basal organic matter to the local population (66Á95%). Consequently, fish condition and individual growth rates are high in these kelp-bed fuelled outer fjord habitats. Our findings demonstrate that baseline variability in the nutritional landscape can result in spatially structured populations, highlighting the importance of spatially-explicit management measures in the sustainable exploitation of reef fishes.

show abstract

“…Growth rate can be influenced by habitat quality (Carbines et al 2004). Male blue cod grow larger on average and at a faster rate than females (Carbines 2004a). Previous size-at-50% maturity and age-at-50% maturity estimates for blue cod in the Marlborough Sounds are between 21-26 cm (Total Length, TL) and three to six years old (MPI 2014).…”

Section: General Introductionmentioning

confidence: 98%

Blue Cod, Parapercis Colias, Maturity, Fecundity, Sex Change, and Potential Drivers of Sex Ratio in The Marlborough Sounds

Brandt¹

View full text Add to dashboard Cite

<p>Blue cod, Parapercis colias (Pinguipedidae), are widely considered to be the most important recreational finfish species in the South Island. However, blue cod have been declining in abundance in the Marlborough Sounds for many years, and currently, sex ratios are highly male- biased. Blue cod are believed to be a socially structured hermaphroditic species whose populations are prone to local depletion. A potting survey in the Marlborough Sounds was carried out by NIWA in 2013, and along with environmental measurements, 3247 blue cod were measured, weighed, sexed, and stage of sexual maturity was classified macroscopically at sea. Gonads from a subsample of these fish were removed and preserved. In Chapter Two, the preserved gonads were processed histologically and a species-specific histological maturity key was developed. Histological and macroscopic maturity classifications and length-at-maturity estimates were compared. Additionally, estimates of spawning frequency and batch fecundity were made using histological and gravimetric methods. In Chapter Three, possible drivers of sex ratio were investigated using the survey data. Density, large male influence, and environmental factors were considered. In Chapter Four, the feasibility of using digital imaging software to age blue cod otoliths was investigated using the OtolithM application in ImagePro Premier. There was poor agreement between macroscopic and histological maturity classifications (20%, overall). Macroscopic methods overestimated the proportion of mature fish at length in the larger sample, which led to biased length-at-50% maturity (L₅₀) estimates. Macroscopic L₅₀ estimates differed markedly from histology estimates. Using histological data, male L₅₀ was 26 cm TL. Histology indicated that there was no length at which 100% of females were mature. Therefore, a three-parameter capped logistic model was used. Histologically, female L₅₀ was 23.6 cm TL, and the Cap was 0.78, indicating the proportion of mature females reached an asymptote at 0.78. Spawning frequency was 4.6 days, and mean relative batch fecundity was 6.5 hydrated oocytes per gram body weight (SD = 3.3). Hermaphroditism was confirmed for blue cod and was macroscopically identifiable. The analyses in Chapter Three indicated that density had some effect on sex ratio, and large males influenced local sex ratios. Finally, the imaging software could not accurately estimate age compared to an expert reader, and it produced highly variable age estimates. This research found that the macroscopic maturity classifications for blue cod were inaccurate, and revision of the macroscopic key is suggested. The biased estimates of L₅₀ from macroscopic data could lead to biased estimates of spawning stock biomass (SSB). Batch fecundity was markedly lower than the previously reported estimates. The finding of a macroscopically identifiable hermaphroditic stage suggested that ‘hermaphrodite’ should be added as a sex class in the macroscopic key. From the GLM in Chapter Three, in more dense populations, the proportion of males increased. This may have been from changes to male mating strategies, or density may influence the occurrence of primary and secondary males. Finally, areas with males > 45 cm TL had a higher proportion of females, suggesting that large males should be protected in order to help balance sex ratios.</p>

show abstract

Age determination, validation, and growth of blue codParapercis colias, in Foveaux Strait, New Zealand

Cited by 11 publications

References 10 publications

A baseline biological survey of the proposed Taputeranga Marine Reserve (Wellington, New Zealand): spatial and temporal variability along a natural environmental gradient

A baseline biological survey of the proposed Taputeranga Marine Reserve (Wellington, New Zealand): spatial and temporal variability along a natural environmental gradient

Trophic ecology drives spatial variability in growth among subpopulations of an exploited temperate reef fish

Blue Cod, Parapercis Colias, Maturity, Fecundity, Sex Change, and Potential Drivers of Sex Ratio in The Marlborough Sounds

Contact Info

Product

Resources

About