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Growth estimates for shark species are mostly derived from length-at-age data, where age information is commonly obtained from hard structures such as vertebrae and dorsal-fin spines. Unfor- tunately, hard structures cannot be used for estimating the age of many shark species, particularly those occurring in deep water or belonging to ancient groups. Alternative methods are therefore required for the estimation of growth for these shark groups. The broadnose sevengill shark Notorynchus cepedianus has very poorly calcified vertebrae that cannot be used for age and growth estimations. Three stochas- tic versions of the von Bertalanffy-Fabens growth model with random parameter k were fitted to length- increment data of captive and of wild tagged and recaptured N. cepedianus from southeastern Australia, California and southern Africa. The model based on a gamma distributed parameter k provided the best fit to the data. Captive females and wild females showed the highest and lowest values of mathematical expectation E(k), whereas wild males and wild females showed the lowest and highest values of mean maximum length L∞, respectively. For a time interval of 1 yr, captive females had the highest length in- crement, whereas wild females had the lowest length increment. Our approach allows accounting for the natural heterogeneity of growth in the estimation of the growth parameters of N. cepedianus, which has not been done previously for captive and wild sharks. This the first study to provide a representative set of growth parameters for male and female N. cepedianus, which is crucial information for the modelling of the population dynamics of this top predator.

Validated age and growth estimates are important for constructing age-structured population dynamic models of chondrichthyan fishes, especially those which are exploited. We review age and growth studies of chondrichthyan fishes, using 28 recent studies to identify areas where improvements can be made in describing the characteristics of ageing structures (both traditional and novel) utilized to estimate ages of sharks, rays, and chimaeras. The topics identified that need consistency include the: (1) terminology used to describe growth features; (2) methods used to both verify and validate age estimates from chondrichthyan calcified structures, especially edge and marginal increment analyses; and (3) the functions used to produce and describe growth parameters, stressing the incorporation of size at birth (L 0) and multiple functions to characterize growth characteristics, age at maturity and longevity.

Age and growth estimates for the shortfin mako, Isurus oxyrinchus, derived from vertebral centra of 258 specimens (118 males, 140 females), ranging in size from 64 to 340 cm fork length (FL) were compared with data from 22 tag- recaptured individuals (74–193 cm FL) and length-frequency data from 1822 individuals (1035 males, 787 females; 65–215 cm FL). Annual bandpair deposition, confirmed by a concurrent bomb radiocarbon validation study, was used as the basis for band interpretation. Validation was further confirmed with a tetracycline-injected male shortfin mako recaptured after being at liberty off South Africa for 1 year and aged at 18 years. Growth rates from tag-recapture analysis (GROTAG) were higher than those derived from vertebral annuli and were only available from sharks up to 193 cm FL at recapture. Modal length-frequency data were used to verify the first four age classes. Growth curves were fit using both von Bertalanffy and Gompertz models. The 3-parameter version of the von Bertalanffy growth function produced the most biologically reasonable values for males, based on observed data (L ∞ = 253 cm FL, K = 0.125 year−1 (estimated longevity = 21 year), and L 0 = 72 cm). The 3-parameter version of the Gompertz growth function produced the most biologically reasonable estimates, for females (L ∞ = 366 cm FL, K = 0.087 year−1 (estimated longevity = 38 year) and L 0 = 88 cm. Males and females were aged to 29 (260 cm FL) and 32 years (335 cm FL), respectively. Both sexes grew similarly to age 11 (207 cm FL, 212 cm FL for males and females, respectively) when the curve leveled in males and continued to rise in females. Age at 50% maturity was estimated at 8 years for males (185 cm FL) and 18 years for females (275 cm FL). The species grows slower, matures later and has a longer life span than previously reported in North Atlantic waters.

Five pandarid (Copepoda) species, Dinemoura producta, D. latifolia, Echthrogaleus coleoptratus, Pandarus bicolor, and Acbtheinus oblongus, were collected from the external body surface of a white shark, Carcharodon carcharias, taken from Morro Bay in the northeastern Pacific Ocean off central California. This is the first report of parasitic copepods collected from C. carcharias captured in the northeastern Pacific along the West Coast of North America. It is proposed that the species-rich infections of some white sharks may be the result of the wide wanderings of individual sharks through waters inhabited by other elasmo-branchs.

White sharks are highly migratory apex predators, globally distributed in temperate, sub-tropical, and tropical waters. Knowledge of white shark biology and ecology has increased recently based on research at known aggregation sites in the Indian, Atlantic, and Northeast Pacific Oceans; however, few data are available for the Northwest Pacific Ocean. This study provides a meta-analysis of 240 observations of white sharks from the Northwest Pacific Ocean between 1951 and 2012. Records comprise reports of bycatch in commercial fisheries, media accounts, personal communications, and documentation of shark-human interactions from Russia (n = 8), Republic of Korea (22), Japan (129), China (32), Taiwan (45), Philippines (1) and Vietnam (3). Observations occurred in all months, excluding October-January in the north (Russia and Republic of Korea) and July-August in the south (China, Taiwan, Philippines, and Vietnam). Population trend analysis indicated that the relative abundance of white sharks in the region has remained relatively stable, but parameterization of a 75% increase in observer effort found evidence of a minor decline since 2002. Reliably measured sharks ranged from 126–602 cm total length (TL) and 16–2530 kg total weight. The largest shark in this study (602 cm TL) represents the largest measured shark on record worldwide. For all countries combined the sex ratio was non-significantly biased towards females (1∶1.1; n = 113). Of 60 females examined, 11 were confirmed pregnant ranging from the beginning stages of pregnancy (egg cases) to near term (140 cm TL embryos). On average, 6.0±2.2 embryos were found per litter (maximum of 10) and gestation period was estimated to be 20 months. These observations confirm that white sharks are present in the Northwest Pacific Ocean year-round. While acknowledging the difficulties of studying little known populations of a naturally low abundance species, these results highlight the need for dedicated research to inform regional conservation and management planning.

Pelagic stingrays, Dasyatis violacea, were collected in southern California in summer–autumn 1994–97. The smallest, 40–45 cm disc width (DW) and 2 kg, were estimated to approach age two. In captive growth and feeding experiments from March 1995 to August 2000, the largest male reached 68 cm DW and 12 kg at estimated age 7 years, and the largest female reached 96 cm DW and 49 kg at estimated age 9 years. The growth data could be fitted with both Gompertz and von Bertalanffy growth functions, but the former produced more reasonable values for size at birth, maximum size, and longevity. Consumption of squid was 6–7% of body mass (BM) per day for juveniles 2 years old and decreased to 1.25% BM day–1 for adults. Food intake for adults was seasonal, with 2 cycles per year with a maximum of ~2.0% and a minimum of 1.0–0.5% BM day–1 from July to October 1998. The data for gross conversion efficiency (K1, based on energy values), collected at 20°C with daily feeding to satiation, could be fitted with a linear regression in the estimated mean age range of 3–6 years (K1 = 0.37 – 0.055 Age).

Knowledge of the age, growth and demography of an organism can be quite useful for managing its fishery. However, for many elasmobranch species, no valid estimates of age, growth and therefore age-specific mortality and natality rates are available. Thus, even though the distribution, abundance, habits and reproduction of a population may be known, no reliable estimates of population growth are possible. As a result, detailed demographic analysis has been completed for only a few shark species (e.g. the California leopard shark, Triakis semlfasciata). All age-determination techniques attempted for the Pacific angel shark (Squatina californica) have met with difficulties. Recently, however, we have accumulated data on 69 tag-recaptures and have used this information to model a von Bertalanffy growth function (VBGF) to predict the growth of this commercially exploited shark species. We performed a demographic analysis of this species, which yielded a net reproductive rate (R0) of 2.25, a generation time (G) of 14.5 years, and an estimate of the instantaneous population growth coefficient (r) of 0.056 year-1, assuming that only natural mortality (M) was occurring, estimated to be 0.2 year-1. When reasonable estimates of fishing mortality (F) are included in the survivorship function, Ro and r are reduced considerably. Presently, Pacific angel sharks first enter the fishery at the same size and age at which they first reproduce. Until accurate estimates of M and Fare available, it would be prudent to set a size limit considerably above the size at first reproduction to protect the Pacific angel shark in California.