Use of the daily egg production method to estimate the stock size of Western Australian sardines (Sardinops sagax)

1996 ◽  
Vol 47 (6) ◽  
pp. 819 ◽  
Author(s):  
WJ Fletcher ◽  
NCH Lo ◽  
EA Hayes ◽  
RJ Tregonning ◽  
SJ Blight
Keyword(s):  
Western Australia ◽  
Egg Production ◽  
Production Method ◽  
Purse Seine ◽  
Batch Fecundity ◽  
Stock Size ◽  
Production Values ◽  
Sardinops Sagax ◽  
Western Australian ◽  
Spawning Biomass

The daily egg production method was used to estimate the spawning biomass of the sardine Sardinops sagax in the Albany region of Western Australia. Plankton surveys covering 10000 - 14000 km² were completed in July of 1991 and 1992 in three to five days using up to three boats. Adult sardines were obtained from the local purse-seine fleet. The spawning area was similar in both years at approximately 3800 km² (1100 nmile²), but the number of eggs collected was larger in 1991 with egg production values of 6.5 per 0.05 m2 day-1 compared with 3.9 per 0.05 m2 day-1 in 1992. The average batch fecundity values were similar (approximately 11000 eggs female-1) as were the proportions spawning (0.13 in 1991; 0.09 in 1992). The calculated biomass estimates were 23 121 t (CV = 0.51) and 16 121 t (CV = 0.44) in 1991 and 1992 respectively.

scholarly journals Predicting habitat to optimize sampling of Pacific sardine (Sardinops sagax)

2011 ◽  
Vol 68 (5) ◽  
pp. 867-879 ◽  
Author(s):  
Juan P. Zwolinski ◽  
Robert L. Emmett ◽  
David A. Demer
Keyword(s):  
Egg Production ◽  
Additive Model ◽  
Production Method ◽  
The United States ◽  
Seasonal Migration ◽  
Sea Surface ◽  
Sampling Effort ◽  
Potential Habitat ◽  
Pacific Sardine ◽  
Sardinops Sagax

Abstract Zwolinski, J. P., Emmett, R. L., and Demer, D. A. 2011. Predicting habitat to optimize sampling of Pacific sardine (Sardinops sagax). – ICES Journal of Marine Science, 68: 867–879. More than 40 years after the collapse of the fishery for Pacific sardine, a renewed fishery has emerged off the west coasts of the United States and Canada. The daily egg production method (DEPM) and acoustic-trawl surveys are performed annually and, to minimize the uncertainties in the estimates, sampling effort needs to be allocated optimally. Here, based on a 12-year dataset including the presence/absence of sardine eggs and concomitant remotely sensed oceanographic variables, a probabilistic generalized additive model is developed to predict spatio-temporal distributions of habitat for the northern stock of Pacific sardine in the California Current. Significant relationships are identified between eggs and sea surface temperature, chlorophyll a concentration, and the gradient of sea surface altitude. The model accurately predicts the habitat and seasonal migration pattern of sardine, irrespective of spawning condition. The predictions of potential habitat are validated extensively by fishery landings and net-sample data from the northeast Pacific. The predicted habitat can be used to optimize the time and location of the DEPM, acoustic-trawl, and aerial surveys of sardine. The method developed and illustrated may be applicable too to studies of other stocks of sardine and other epipelagic fish in other eastern boundary, upwelling regions.

scholarly journals Estimates of batch fecundity and spawning fraction for the southern stock of horse mackerel (Trachurus trachurus) in ICES Division IXa

2009 ◽  
Vol 66 (4) ◽  
pp. 617-622 ◽  
Author(s):  
Patrícia Gonçalves ◽  
Ana Maria Costa ◽  
Alberto G. Murta
Keyword(s):  
Egg Production ◽  
Production Method ◽  
Horse Mackerel ◽  
Batch Fecundity ◽  
Trachurus Trachurus ◽  
Absolute Abundance ◽  
Female Total ◽  
Stock Biomass ◽  
Spawning Stock ◽  
Ovulatory Follicles

Abstract Gonçalves, P., Costa, A. M., and Murta, A. G. 2009. Estimates of batch fecundity, and spawning fraction for the southern stock of horse mackerel (Trachurus trachurus) in ICES Division IXa. – ICES Journal of Marine Science, 66: 617–622. Since 1995 the annual egg production method has been applied triennially to the southern stock of horse mackerel (Trachurus trachurus) in the Northeast Atlantic (ICES Division IXa). This method assumes that fecundity is determinate, but increasing evidence indicates that horse mackerel are indeterminate spawners. The daily egg production method (DEPM) does not rely on the assumption of determinate fecundity, making it the appropriate method for this species. Therefore, we reanalysed samples collected from previous surveys (2002, 2004, 2005, and 2007) to obtain estimates for batch fecundity and spawning fraction, which are important DEPM parameters. The estimates of batch fecundity are around 200 oocytes g−1 of female (total ovary-free weight). Several criteria were used to estimate spawning fraction (migratory nucleus stage, hydrated oocytes, and post-ovulatory follicles) and all showed the same trend among years, varying between 0.10 and 0.30 d−1. The estimates were significantly different among methods, but those differences were similar across surveys, indicating that a consistent bias would be reflected in the final spawning-stock biomass (SSB) estimates obtained from the DEPM. Until further information is available regarding the accuracy of the criteria used to estimate spawning fraction, the southern horse mackerel SSB estimates from the DEPM should only be taken as indicative of trends rather than measures of absolute abundance.

scholarly journals Atlantic mackerel daily spawning dynamics and implications for batch fecundity estimations

2018 ◽  
Vol 75 (5) ◽  
pp. 1647-1654
Author(s):  
K Ganias ◽  
D Marmara ◽  
A Solla ◽  
D Garabana ◽  
R Dominguez-Petit
Keyword(s):  
Egg Production ◽  
Time Window ◽  
Production Method ◽  
Time Of Day ◽  
Batch Fecundity ◽  
Atlantic Mackerel ◽  
Spawning Frequency ◽  
Scomber Scombrus ◽  
Daily Spawning

Abstract The present study contributes to a better understanding of the daily spawning dynamics of southern NEA mackerel (Scomber scombrus) with implications for the estimation of batch fecundity. It shows that there is a time window during the day, mainly in the afternoon, during which the advanced oocyte mode in imminent spawners separates from the remaining, smaller oocytes. This synchronicity in the separation of the spawning batch amongst imminent spawners corroborates evidence for the existence of daily spawning synchronicity in the population. This is particularly important for applications of the daily egg production method, DEPM, because such pattern facilitates both the ageing of eggs for the estimation of the daily egg production at sea and the ageing of postovulatory follicles for the estimation of spawning frequency. For NEA mackerel, batch fecundity could only be measured when a clear hiatus was established between the spawning batch and the smaller oocytes. Hydrated females that do not show such hiatus would not be valid for batch fecundity measurements suggesting that the “hydrated oocytes method” is not fully applicable for this stock. Knowing the time of day at which the batch is separated, will facilitate the sampling of valid females for the estimation of batch fecundity.

Evaluating the use of the Daily Egg Production Method for stock assessment of blue mackerel, Scomber australasicus

2009 ◽  
Vol 60 (2) ◽  
pp. 112 ◽  
Author(s):  
T. M. Ward ◽  
P. J. Rogers ◽  
L. J. McLeay ◽  
R. McGarvey
Keyword(s):  
Egg Production ◽  
Early Stage ◽  
Stock Assessment ◽  
Production Method ◽  
Spawning Area ◽  
Eastern Australia ◽  
Genetic Techniques ◽  
Ovulatory Follicles ◽  
Improved Methods ◽  
Spawning Biomass

The present study evaluates the suitability of the Daily Egg Production Method (DEPM) for stock assessment of blue mackerel, Scomber australasicus and assesses methodological options for future applications. In southern Australia, estimates of mean daily egg production were higher for Californian Vertical Egg Tow (CalVET) nets than bongo nets, and in eastern Australia, were higher in October 2003 than July 2004. Estimates of spawning area for southern Australia were three times higher for bongo nets than CalVET nets. Similar estimates of spawning area were obtained using standard (manual) gridding and natural neighbour methods. Large samples and reliable estimates of all adult parameters were obtained for southern Australia. Relatively few spawning adults were collected off eastern Australia. Preliminary best estimates of spawning biomass for southern and eastern Australia were 56 228 t and 29 578 t, respectively, with most estimates within the ranges of 45 000–68 000 t and 20 000–40 000 t respectively. The DEPM is suitable for stock assessment of S. australasicus. Several technical refinements are required to enhance future applications, including: genetic techniques for identifying early stage eggs; a temperature–egg development key; improved methods for sampling adults off eastern Australia; and measurements of the degeneration rates of post-ovulatory follicles at several temperatures.

Preliminary assessments of stocks of the Western Australian crayfish, Panulirus cygnus George

1966 ◽  
Vol 17 (1) ◽  
pp. 93 ◽  
Author(s):  
BK Bowen ◽  
RG Chittleborough
Keyword(s):  
Western Australia ◽  
Fishing Effort ◽  
Total Catch ◽  
Catch Per Unit Effort ◽  
Stock Size ◽  
Unit Effort ◽  
Exploitation Rate ◽  
Panulirus Cygnus ◽  
Western Australian ◽  
Closed Period

Total catch of Panulirus cygnus in Western Australia rose from 0.6 million lb in 1944-45 to 21.4 million Ib in 1962-63. Fishing effort increased rapidly with the result that the catch per unit effort declined progressively. Effort has been limited by regulation since 1963. From records of catch and effort from specified areas at intervals of one month throughout each season, estimates were made of mortality coefficients (Z1, F, and M1) and catchability coefficient (q). Stock size, recruitment, and exploitation rates were then estimated. As the seasonal catch per unit effort followed the same trend throughout all fishing areas, the detailed results from the selected areas have been applied to the whole fishery. The fishable stock, originally of approximately 140 million lb, had declined to some 35 million lb by 1963. Exploitation rate rose as effort was increased, and then levelled off (generally at above 60%), further increase in fishing effort resulting in a fall in the catchability coefficient rather than a change in the exploitation rate. Because of the high exploitation rate in recent years, the fishable stock available on the grounds at the opening of a season is largely dependent on recruitment (by growth) of juveniles during the preceding closed period. This recruitment has been diminishing from year to year, apparently because of mortality of undersize (pre-recruit) crayfish handled in fishing pots. Provision of escape gaps in all fishing pots is recommended. A sustainable level of catch might be 16,000,000±2,000,0001b per year if recruitment can be stabilized. Some further restriction of fishing effort might be necessary.

Spawning biomass of Argentine anchovy (Engraulis anchoita) from 1996 to 2004 using the Daily Egg Production Method

2008 ◽  
Vol 89 (4) ◽  
pp. 829-837 ◽  
Author(s):  
Marcelo Pájaro ◽  
Gustavo J. Macchi ◽  
Ezequiel Leonarduzzi ◽  
Jorge E. Hansen
Keyword(s):  
Regional Differences ◽  
Egg Production ◽  
Basic Research ◽  
Production Method ◽  
Mean Values ◽  
Spawning Frequency ◽  
Spawning Stock ◽  
The Mean ◽  
Annual Means ◽  
Spawning Biomass

The Daily Egg Production Method (DEPM) was used to compute spawning biomass of Engraulis anchoita off Argentina. Estimates of the daily egg production (P0) for the northern stock ranged from 594 to 936 eggs m−2, whereas the annual means of the Patagonian stock ranged from 185 to 605 eggs m−2. The mean values estimated for the Argentine anchovy DEPM parameters were characterized by inter-annual differences greater than inter-regional differences with the exception of P0. For the northern population, the estimates of mean weight of mature females ranged from 15 to 26 g, the relative batch fecundity from 414 to 600 eggs g−1, the spawning frequency (S) from 0.078 to 0.179, and the females ratio from 0.519 to 0.622 of the spawning stock. The estimates corresponding to the Patagonian stock were similar being 15 to 24 g, 418 to 583 eggs g−1, 0.079 to 0.244, and 0.394 to 0.590, respectively. The annual estimates of the spawning biomass for the northern and Patagonian populations ranged between 1.6–3.5 and 0.3–1.5 million metric tons, respectively. A weakness in the application of DEPM was the low precision in the estimation of the daily egg production and the spawning fraction. Alternative methodologies to increase the precision of P0 and S are discussed. In spite of the high variance of the spawning biomass estimates, the use of DEPM offers valuable information to adjust acoustic estimates and provides time series of anchovy population size and biological parameters for basic research.

Reproductive biology of blue mackerel, Scomber australasicus, off southern and eastern Australia: suitability of the Daily Egg Production Method for stock assessment

2009 ◽  
Vol 60 (2) ◽  
pp. 187 ◽  
Author(s):  
P. J. Rogers ◽  
T. M. Ward ◽  
L. J. McLeay ◽  
M. Lowry ◽  
R. J. Saunders ◽  
...  
Keyword(s):  
Reproductive Biology ◽  
Egg Production ◽  
Stock Assessment ◽  
Fork Length ◽  
Production Method ◽  
Spawning Season ◽  
Batch Size ◽  
Batch Fecundity ◽  
Eastern Australia ◽  
Mature Fish

The present study investigated the reproductive biology of blue mackerel (Scomber australasicus) off southern and eastern Australia and assessed the suitability of the Daily Egg Production Method (DEPM) for future stock assessment. This analysis revealed that S. australasicus is a serial spawner with asynchronous oocyte development and indeterminate fecundity. S. australasicus spawns between November and April off southern Australia and between July and October off eastern Australia. In southern Australia, ~50% of males and females were mature at 236.5 and 286.8 mm fork length (FL), respectively. Size at ~50% maturity could not be estimated reliably for eastern Australia owing to the smaller proportion of mature fish in samples. Mean spawning frequencies ranged from 2 to 11 days off southern Australia. Batch fecundity was related to fish size and mean batch size was 69 894 ± 4361 oocytes per batch and 134 oocytes per g of weight. The timing and duration of the spawning season, size at maturity, spawning frequency and batch fecundity of S. australasicus off southern Australia were consistent with those of S. japonicus in the northern Pacific Ocean. The present study’s estimates of adult reproductive parameters of S. australasicus off southern Australia were suitable for the application of the DEPM for estimating spawning biomass. Collecting representative samples of mature fish from waters off eastern Australia during the spawning season is a high priority for future stock assessment of this species.

Spawning Biomass Estimates of Chub Mackerel Scomber japonicus of Pacific Subpopulation off Central Japan by a Daily Egg Production Method.

1999 ◽  
Vol 65 (4) ◽  
pp. 695-702 ◽  
Author(s):  
Chikako Watanabe ◽  
Takayuki Hanai ◽  
Kiyomi Meguro ◽  
Ryuta Ogino ◽  
Ryo Kimura
Keyword(s):  
Egg Production ◽  
Production Method ◽  
Scomber Japonicus ◽  
Chub Mackerel ◽  
Central Japan ◽  
Spawning Biomass
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