Steven E. Campana

University of Iceland | HI · Faculty of Life and Environmental Sciences

The shortfin mako (Isurus oxyrinchus), porbeagle (Lamna nasus), and blue shark (Prionace glauca) are three frequently caught shark species in the northwestern Atlantic Ocean. Satellite tagging studies show that all three species range widely across many national boundaries but spend up to 92% of their time on the high seas, where they are largely u...

Despite their notoriety and role as apex predators, the longevity of large pelagic sharks such as the porbeagle (Lamna nasus) and shortfin mako (Isurus oxyrinchus) is unknown. Vertebral growth bands provide an accurate indicator of age in young porbeagle, but age validation has never been reported for any large shark species past the age of sexual...

Otolith microstructure examination has found an increasing number of applications in recent years. However, few workers have critically assessed the assumptions upon which the age and growth inferences are based or considered the potential for environmental modification of microstructural features. This paper reviews present applications and their...

A review of 862 otolith-oriented papers published since the time of the 1998 Otolith Symposium in Bergen, Norway suggests that there has been a change in research emphasis compared to earlier years. Although close to 40% of the papers could be classifed as 'annual age and growth' studies, the remaining papers were roughly equally divided between st...

Prior experience is as much an eye opener in science as it is in life, and often results in increased efficiency, greater productivity and reduced stress. While some actions and behaviours must be experienced first-hand to be appreciated, there are some behavioural patterns that can be readily absorbed from others, allowing the learning curve to be...

1. Substantial global population declines in pelagic sharks have led to the introduction of management and conservation measures, including gear restrictions and no-retention policies, to curb declines and encourage stock recovery. As the rate of discarding sharks increases, there is a growing need to understand prognostic factors that influence th...

Large-scale, climate-induced synchrony in the productivity of fish populations is becoming more pronounced in the world's oceans. As synchrony increases, a population's 'portfolio' of responses can be diminished, in turn reducing its resilience to strong perturbation. Here we argue that the costs and benefits of trait synchronization, such as the e...

Ages of Chilean jack mackerel (Trachurus murphyi) in the southern Pacific Ocean were validated using three methods: 1) daily microincrement readings in sagittal otoliths of young-of-the year (YOY) fish to validate the first annulus; 2) modal progression of strong year-classes (PSYC) to validate the first, second and third annuli, and 3) bomb radioc...

Blue shark (Prionace glauca) is amongst the most abundant shark species in international trade, however this highly migratory species has little effective management and the need for spatio-temporal strategies increases, possibly involving the most vulnerable stage or sex classes. We combined 265,595 blue shark observations (capture or satellite ta...

Animals actively select the most suitable habitat in terms of fitness, much of which is mediated by temperature. We reconstructed population abundance, oxygen isotope and temperature chronologies for the Icelandic and the Northeast Arctic (NEA) cod (Gadus morhua) populations to determine if their temperature selectivity over the last 100 years was...

Global warming is increasing ocean temperatures, forcing marine organisms to respond to a suite of changing environmental conditions. The stable oxygen isotopic composition of otoliths is often used as an index of temperature exposure, but the accuracy of the resulting temperature reconstructions in wild, free-swimming Atlantic cod (Gadus morhua) h...

Otolith shape has previously been used to identify ecotypes within the Icelandic cod ( Gadus morhua) stock, using DST profiles to validate the results. Fish otolith shape variation has repeatedly been found to be largely determined by growth rate. To examine the effect of growth rate on the relationship between otolith shape and cod ecotypes (using...

106,107 ✉ replying to A. V. Harry & J. M. Braccini Nature https://doi.org/10.1038/s41586-021-03463-w (2021) Our global analysis 1 estimated the overlap and fishing exposure risk (FEI) using the space use of satellite-tracked sharks and longline fishing effort monitored by the automatic identification system (AIS). In the accompanying Comment, Harry...

This article is a response to Murua et al.'s Matters Arising article in Nature, "Shark mortality cannot be assessed by fishery overlap alone," which arose from arising from N. Queiroz et al. Nature https://doi.org/10.1038/s41586-019-1444-4 (2019).

The isotopic composition of inorganic carbon in otoliths ( δ 13 C oto ) can be a useful tracer of metabolic rates and a method to study ecophysiology in wild fish. We evaluated environmental and physiological sources of δ 13 C oto variation in Icelandic and Northeast Arctic (NEA) cod ( Gadus morhua ) over the years 1914–2013. Individual annual grow...

Otolith shape has previously been used to identify ecotypes within the Icelandic cod (Gadus morhua) stock, using DST profiles to validate the results. Fish otolith shape variation has repeatedly been found to be largely determined by growth rate. To examine the effect of growth rate on the relationship between otolith shape and cod ecotypes (using...

Otolith biochronologies combine growth records from individual fish to produce long-term growth sequences, which can help to disentangle individual from population-level responses to environmental variability. This study assessed individual thermal plasticity of Atlantic cod (Gadus morhua) growth in Icelandic waters based on measurements of otolith...

The distributional response of marine fishes to climate warming would be expected to be very different than that of homeothermic birds and mammals, due both to more direct thermal effects on poikilothermic fish physiology and on reduced habitat fragmentation. In this study, we use a combination of linear models and graphical tools to quantify three...

Horizon scanning is an increasingly common strategy to identify key research needs and frame future agendas in science. Here, we present the results of the first such exercise for the field of sclerochronology, thereby providing an overview of persistent and emergent research questions that should be addressed by future studies. Through online corr...

Marine ecosystems, particularly in high‐latitude regions such as the Arctic, have been significantly affected by human activities and contributions to climate change. Evaluating how fish populations responded to past changes in their environment is helpful for evaluating their future patterns, but is often hindered by the lack of long‐term biologic...

Analysis of growth increments in the hard parts of animals, e.g. fish otoliths, can be used to assess how organisms respond to variability in environmental conditions. In this study, mixed-effects models were applied to otolith data simulated for two hypothetical fish populations with assumed biological parameters and known growth response to envir...

Climate warming at high latitudes has long been expected to exceed that predicted for tropical and temperate climes, but recent warming in the Arctic has exceeded even those expectations[1].The geophysical consequences of this warming are reasonably well established[2], but the impacts on freshwater fauna are poorly understood. Here we use a large-...

Conservation and management strategies for endangered and threatened species require accurate estimates of demographic parameters such as age and growth. The whale shark, Rhincodon typus, is the largest fish in the world and is highly valued in the eco-tourism sector. Despite conservation concerns and advances in our understanding of their life his...

Increasing water temperatures are predicted around the globe, with high amplitudes of warming in Subarctic and Arctic regions where Atlantic cod (Gadus morhua) populations currently flourish. We reconstructed oxygen isotope and temperature chronologies from Icelandic cod otoliths, one of the largest cod stocks in the world, to determine if cod move...

Effective ocean management and conservation of highly migratory species depends on resolving overlap between animal movements and distributions and fishing effort. Yet, this information is lacking at a global scale. Here we show, using a big-data approach combining satellite-tracked movements of pelagic sharks and global fishing fleets, that 24% of...

Oral presentation of the early results of our analysis of long term temporal stability of Northeast arctic cod otolith shape.

Predation and mortality are often difficult to estimate in the ocean, which hampers the management and conservation of marine fishes. We used data from pop-up satellite archival tags to investigate the ocean predation and mortality of adult Atlantic salmon (Salmo salar) released from 12 rivers flowing into the North Atlantic Ocean. Data from 156 ta...

Long-lived species share life history traits such as slow growth, late maturity, and low fecundity, which lead to slow recovery rates and increase a population’s vulnerability to disturbance. The Greenland shark (Somniosus microcephalus) has recently been recognized as the world’s longest-lived vertebrate, but many questions regarding its biology,...

Recent studies using otolith microstructure analysis have suggested that the duration of the juvenile stage in anchoveta (Engraulis ringens) is shorter than previously suspected, which suggests that the ages being entered into the traditional age-based stock assessment are incorrect. However, the interpretation of young pelagic fish otoliths remain...

The growth rates of freshwater fish in the Arctic would be expected to be very low, but some previous studies of lake whitefish (Coregonus clupeaformis) have reported relatively rapid growth and longevity estimates of less than 15 years. We used bomb radiocarbon chronologies to validate an ageing method based on otolith sections for lake whitefish...

Spatial and temporal variations in size for fish at different reproductive states were investigated in the Barents Sea between 1997 and 2016. The study focused on fish caught in August/September, separated into four reproductive states based on gonad and otolith reading. Variations in size were interpolated using ordinary spatial kriging and contou...

We present the growth cessation model, which is designed for species, such as some tropical tunas, that have an apparent linear relationship between length and age, followed by a marked reduction of growth after the onset of sexual maturity. The growth curve simply assumes linear growth for the youngest individuals and then uses a logistic function...

Supplementary material for associated publication.

We examined four species of sea pen (Anthoptilum grandiflorum, Halipteris finmarchica, Pennatula aculeata and Pennatula grandis) collected from the Gulf of St. Lawrence and mouth of the Laurentian Channel, eastern Canada. An exponential length-weight relationship was found for all four species, where growth in weight was progressively greater than...

Herein, we use genetic data from 277 sleeper sharks to perform coalescent-based modeling to test the hypothesis of early Quaternary emergence of the Greenland shark (Somniosus microcephalus) from ancestral sleeper sharks in the Canadian Arctic-Subarctic region. Our results show that morphologically cryptic somniosids S. microcephalus and Somniosus...

Northwest Atlantic (NWA) redfish (Sebastes mentella and Sebastes fasciatus) stocks are currently assessed using survey indicators and age-aggregated production models rather than age-based models because routine age readings are not available due to the difficulty in obtaining reliable measurements for these fish. However, recruitment is highly var...

Knowledge of age and growth parameters is vital to the conservation and management of white sharks (Carcharodon carcharias), but ages have not been validated for all populations and growth rates can vary regionally. Bomb radiocarbon (14C) analyses conducted on four individual white sharks [329, 414, 487, and 537 cm fork length (FL)] from the southw...

We examined spatial variation in otolith geochemistry as a natural tag in juvenile Atlantic cod to resolve geographic patterns during early life history. Individuals from 54 inshore sites spanned five embayments in eastern Newfoundland. Otolith composition differed at all spatial scales and related inversely to spatial scale. Classification analysi...

Sharks and rays are among the most endangered group of marine animals and include many species for which there is little information on abundance and distribution. There are no global abundance trends for elasmobranchs as a group, and very few robust regional trend indicators. Population-level stock assessments, which provide the most reliable inde...

Global discards of sharks greatly exceed reported landings, yet there are few estimates of mortality after release. Based on more than 21 000 fisheries observer records and the results of 109 popup satellite archival tags, all sources of fishing-induced mortality (harvest, capture, and post-release) were estimated for blue sharks (Prionace glauca),...

A winning feature of naturally-induced fish tags is their simultaneous appearance on the entire group or population, at no expense to the researcher. The challenge then becomes the search for a marker that is sufficiently distinct that it will allow clear identification of the group of interest. Elemental and isotopic fingerprints, genetic markers,...

As the commonly-used von Bertalanffy growth function (VB) does not explicitly incorporate changes in growth due to allocation of energy to reproduction, a more flexible function could be used when attempting to model juvenile and adult growth simultaneously. Here we review biphasic growth models, with emphasis on those that explicitly incorporate t...

An extant stock of wild pallid sturgeon Scaphirhynchus albus persists in the fragmented upper Missouri River basin of Montana and North Dakota. Although successful spawning and hatch of embryos has been verified, long-term catch records suggest that recruitment has not occurred for several decades as the extant stock lacks juvenile size classes and...

The objective of this study was to determine the size and maturity status of the male blue sharks Prionace glauca attempting to mate with small, immature females in the north-west Atlantic Ocean. The relationship between male curved fork length (LFC ) and jaw gape was used in conjunction with the diameter of the mating scar to estimate the LFC and...

Both conventional and satellite tagging studies indicate that blue sharks are widely distributed and highly migratory across both Atlantic Canada and the North Atlantic waters, with no evidence of year-round residency in Canadian waters. There is no fishery-independent index of abundance for blue sharks in Canadian waters. Standardized catch rates...

Many past attempts to age deep-water redfish (Sebastes mentella) and Acadian redfish (S. fasciatus) in the northwest Atlantic have been stymied by inappropriate ageing methods, the absence of age validation and the failure to differentiate among species. Herein we report substantial improvements in methods for ageing Sebastes spp. by linking the es...

An Ecological Risk Assessment (ERA; also known as Productivity and Susceptibility Analysis, PSA) was conducted on sixteen species (15 sharks and 1 ray) or 20 stocks of pelagic elasmobranchs to assess their vulnerability to pelagic longline fisheries in the Atlantic Ocean. This was a quantitative assessment consisting of a risk analysis to evaluate...

The chemical composition of calcified structures in fish (otoliths, spines, rays, scales, and vertebrae) has been identified as a useful natural marker of stock structure. This application depends on geographic variation in water chemistry or other factors (e.g., temperature) that influences the chemistry of the calcified structure such that fish t...

The jack mackerel, Trachurus murphy Nichols 1920, is a very important commercial carangid in the southern Pacific Ocean. Despite their importance age determination is still a controversial issue in this species. To date jack mackerel ageing, achieved by reading annual rings in whole and sectioned otoliths, has been used for stock assessment from 19...

Oxygen isotope ratios from fish otoliths are used to discriminate marine stocks and reconstruct past climate, assuming that variations in otolith δ18O values closely reflect differences in temperature history of fish when accounting for salinity induced variability in water δ18O. To investigate this, we exploited the environmental and migratory dat...

Methods for confirming the accuracy of age determination methods are reasonably well established in fishes, but the millions of routine age determinations which take place every year require their own quality control protocols. In contrast, methods for ensuring accuracy in age determination of monodontids and other marine mammals are still being de...