The physical basis for recruitment variability in fish populations

Rothschild, Brian J.; Osborn, Thomas R.; Dickey, T. D.; Farmer, Debbie

doi:10.1093/icesjms/45.2.136

Cited by 14 publications

(9 citation statements)

References 14 publications

(17 reference statements)

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“…Examples of changes in fecundity that could provide a compensatory mechanism serving to stabilise fish populations have been reported (Nikolsky 1969; Nikolsky et al . 1973; Rothschild et al . 1989).…”

Section: Understanding Compensationmentioning

confidence: 99%

Compensatory density dependence in fish populations: importance, controversy, understanding and prognosis

et al. 2001

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Density‐dependent processes such as growth, survival, reproduction and movement are compensatory if their rates change in response to variation in population density (or numbers) such that they result in a slowed population growth rate at high densities and promote a numerical increase of the population at low densities. Compensatory density dependence is important to fisheries management because it operates to offset the losses of individuals. While the concept of compensation is straightforward, it remains one of the most controversial issues in population dynamics. The difficulties arise when going from general concepts to specific populations. Compensation is usually quantified using some combination of spawner–recruit analysis, long‐term field monitoring or manipulative studies, and computer modelling. Problems arise because there are limitations to each of these approaches, and these limitations generally originate from the high uncertainty associated with field measurements. We offer a hierarchical approach to predicting and understanding compensation that ranges from the very general, using basic life‐history theory, to the highly site‐specific, using detailed population models. We analyse a spawner–recruit database to test the predictions about compensation and compensatory reserve that derive from a three‐endpoint life‐history framework designed for fish. We then summarise field examples of density dependence in specific processes. Selected long‐term field monitoring studies, manipulative studies and computer modelling examples are then highlighted that illustrate how density‐dependent processes led to compensatory responses at the population level. Some theoretical and empirical advances that offer hope for progress in the future on the compensation issue are discussed. We advocate an approach to compensation that involves process‐level understanding of the underlying mechanisms, life‐history theory, careful analysis of field data, and matrix and individual‐based modelling. There will always be debate if the quantification of compensation does not include some degree of understanding of the underlying mechanisms.

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Section: Understanding Compensationmentioning

confidence: 99%

Compensatory density dependence in fish populations: importance, controversy, understanding and prognosis

et al. 2001

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“…Links between larval or post-larval survival and hydrographic conditions have been demonstrated for many species (Houde 1989) but the mechanism by which larvae at different ages maximise their food intake are extremely complex (Rothschild et al 1989). For food supply to have a major effect on larval survival, the events influencing food abundance do not have to be catastrophic.…”

Section: Regression Equationmentioning

confidence: 99%

Links between climate variation and the year class strength of New Zealand hoki (Macruronus novaezelandiae) Hector

Livingston¹

2000

New Zealand Journal of Marine and Freshwater Research

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Hoki (Macruronus novaezelandiae)Hector year class strength (YCS) varies substantially from year to year. In this study, potential links between hoki YCS estimates for western and eastern stocks, and time series of the Southern Oscillation Index (SOI), satellite sea surface temperatures (SST), synoptic weather patterns, depth of the mixed layer (western stock only), and wind speeds are explored. The results indicate that favourable recruitment in the western stock is correlated with a negative SOI and associated conditions such as lower SSTs, early onset of deep water mixing and synoptic weather patterns that result in a higher incidence of southwest (SW) flow. Favourable recruitment in the eastern stock appears to be correlated with periods of westerly flow, particularly from the SW, but also the north-west (NW). Regression studies showed that when inter-correlation was minimised, 95% of the variation in YCS of the western stock was explained by four variables-SOI in autumn, the onset of winter mixing, SST in spring, and NW spring weather patterns. In the eastern stock, 88% of the variation in YCS was explained by SW and NW winter weather patterns and the average speed of SW winds in winter through Cook Strait. Although the underlying mechanisms are not proven, the climate variables which appear to be linked to favourable recruitment for both western and eastern stocks, also favour upwelling and the physical transportation of larval hoki from the spawning grounds into their respective inshore nursery areas. M99026

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“…The species is thought to be substantially overexploited (Caton & Majkowski 1987). However, little is known of its early life history and nothing is known of the patterns of dispersal and rates of mortality of the larvae, although it is believed that larval mortality is an important component of recruitment variability (Cushing 1975, Rothschild et al 1989. It is also considered that the most important source of bias in estimating e g g production is likely to b e mortality during the period from spawning to the stage on which the estimate is based (Saville & Schnack 1981).…”

Section: Introductionmentioning

confidence: 99%

Advection, dispersion and mortality of a patch of southern bluefin tuna larvae Thunnus maccoyii in the East Indian Ocean

Davis¹,

Lyne²,

Jenkins³

1991

Mar. Ecol. Prog. Ser.

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ABSTRACT. h4ortality rate of southern bluefin tuna larvae Thunnus rnaccoyii was determined from measurements of a large, high density patch of larvae in the East Indian Ocean made In January-February 1987. An advection-diffusion-mortality model that improves on elliptical spread models was used to model changes in the patch over a period of 6 d. The patch at the start of sampling consisted of a distinct cohort of larvae 7 to 8 d old. Diffusion in subsequent 2 d intervals was slow (1.02 to 1.5 m2 S-') but within the bounds observed for patch scales in the order of a few kilometres widr. Intensifying southwesterly winds were opposed by advect~on with a southwestward drift of about 6 cm S l . The origlnal intent~on of using a free-dnftmg drogue to track the centre of the patch, and thereby account for the advective process, was not successful because of the relative drift of buoy and larval patch. Instantaneous mortality (Z) was estimated to b e 0.66 d-' (a daily survival rate of 52 '::,). This is the first time the mortality of tuna larvae has been directly estimated in the open ocean.

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The physical basis for recruitment variability in fish populations

Cited by 14 publications

References 14 publications

Compensatory density dependence in fish populations: importance, controversy, understanding and prognosis

Compensatory density dependence in fish populations: importance, controversy, understanding and prognosis

Links between climate variation and the year class strength of New Zealand hoki (Macruronus novaezelandiae) Hector

Advection, dispersion and mortality of a patch of southern bluefin tuna larvae Thunnus maccoyii in the East Indian Ocean

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