Modern Protocols, Procedures, and Analytical Tools for Determining Age and Growth of Free-Ranging Animals

Age and growth information is one of the fundamental building blocks of fisheries and wildlife science. Metrics describing the performance of free-ranging populations can be derived from this information. Consequently, managers and researchers expend much effort collecting, processing, and interpreting hard structures from animals. Therefore, it is important to incorporate procedures to ensure data quality from collection to interpretation. Many investigators and laboratories have developed their own methods to validate and standardize methods and data. New tools and techniques have been recently developed that enable validation and quality control in ageing investigations. Some of these can be adopted by anyone, while others may require significant resources or collaboration to implement. The purpose of this symposium and workshop is to facilitate communication and collaboration among ageing laboratories of all types. The goal of the symposium is to present case studies of quality control and validation techniques. Presentations will focus on innovative approaches and protocols for developing and validating ages from scales, otoliths, bones, and other hard structures useful to researchers and biologists. Participants will gain updated knowledge of recent advances in methods and technology and thus their age and growth pattern interpretation skills, ultimately enhancing fisheries and wildlife management.

8:00AM A Problem for the Ages: Quality Assurance and Control Techniques Used to Obtain Reliable Age Structure Information
  Micah Davison, Timothy Copeland, Carlos Camacho
Information reliability is directly related to data quality. The Nampa Research Anadromous Ageing Laboratory provides age information on threatened and endangered Idaho salmonids to multiple state, tribal, and federal agencies. This information is based on the interpretation of calcified structures, specifically fin rays and scales, and associated biometric data. A critical component of our operation is the quality assurance and control protocols designed to minimize error and their consequences while efficiently utilizing limited resources. Here we discuss three key process phases: collection, interpretation, and distribution. For each we have developed quality control procedures to maximize information quality and reliability. We implemented training protocols to standardize competencies across each process phase and maintain quality standards. Pattern variability across species, life stage, space and seasons are a major source of potential error. In order to acclimate readers to seasonal pattern variability in saltwater ages and assess reader accuracy, samples of known age are read before the main workload. For juvenile samples, we constructed past seasonal summaries, which are reviewed prior to ageing samples from each location. The combination of seasonal calibration with post hoc analysis, such as length-at-age outliers, provides effective quality control that can be adapted to any ageing program.
8:20AM Utilizing the Image-Pro Otolith APP to Easily Analyze Otolith and Scales
  Rick Logemann
A leader in the digital imaging analysis for over 35 years, Media Cybernetics has developed solutions that have been applied across many industries. Engineering products for researchers to deliver better and more consistent results. The latest version of software Image-Pro carries on this philosophy by improving our macro language as well as a user-friendly APP development tool, resulting in a flexible solution. The Image-Pro Otolith APP is one example of those solutions. Powerful analysis engineered into an easy to use workflow is also adaptable to your needs. Work directly with Media Cybernetics engineers to develop your own APP. Discover how the flexibility and functionality can be utilized in your lab to easily accelerate your research.
8:40AM The Use of PIT Tags and GSI to Validate Ages Estimated from Scales of Salmonids Collected at Bonneville Dam
  Jeffrey K. Fryer
Salmonids have been trapped at Bonneville Dam since 1985 and scale sample to estimate age composition of Sockeye, Chinook, and steelhead. Until recently, age validation was not possible since all fish were of unknown age. With increasing numbers of juvenile salmonids being PIT tagged (though returns typically comprise less than 1% of adults sampled), it has become possible to compare scale ages with age since PIT tagging. Also, advances in genetic stock identification techniques, most notably Parental Based Tagging (PBT), have provided age data on up to 30% of steelhead and Chinook sampled. Corroboration between both PIT-tag and PBT-derived ages and scale ages have consistently been above 95%. With faster turnaround of genetics samples (generally within two weeks from sampling), we have switched from reviewing PBT data post-season and adjusting scale ages to waiting until PBT data is available prior to scale ageing. This allows us to incorporate PBT age data (and information on scale patterns gleaned from those PBT ages) into the scale ageing process, resulting in more accurate ageing with less time spent.
9:00AM The Use of Multiple Techniques to Validate Ages from Naturally Reproducing Steelhead
  Carlos Camacho, Micah Davison, Leslie Reinhardt, Timothy Copeland
The ability to assign accurate ages using non-lethal structures is vital to calculate cohort productivity for species with a wide range of life histories that are at low abundances. Validation of scale ages with reliable, independent methodologies at each life history stage is not easily obtained for many species, such as naturally reproducing steelhead. However, advancements in tag technology and the development of genetic “tags” have expanded age validation opportunities. In this paper, we use PIT (passive integrated transponder) tags and PBT (parental based tag genotyping) to validate the saltwater, freshwater, and total ages from steelhead scales in two related studies. In the first study, scale saltwater ages were in agreement with 96% of the PIT tag ages. In the second study, scale freshwater ages were in agreement with 93% of the PBT ages. Scale total ages were in agreement with 90% of the PBT total ages. Comparing both studies shows that most of the uncertainty in total age assignments comes from the freshwater phase. Using multiple techniques to validate assigned ages is possible for steelhead in the Snake River basin and having reliable ages provides a crucial piece of information needed to assess population viability and status.
9:20AM Improvements to Coho Salmon Scale Ageing in Southeast Alaska
  Justin T. Priest, Julie Bednarski, Sara Miller, Leon Shaul, Lorna Wilson
Accurate ageing of fish stocks is fundamental to age-structured stock assessment of salmon populations. Stocks of Coho Salmon Oncorhynchus kisutch in Southeast Alaska are aged using circuli in scales and historically were difficult to age because of unique environmental conditions causing thermal abnormalities. To determine known ages of wild Coho Salmon stocks in Berners River and Hugh Smith Lake, Alaska, emergent fry were tagged with half-length coded-wire tags and recovered 1–3 years later during smolt outmigration, 1995–2005. Smolt scales were collected and paired with tag release data. Results demonstrated that agers had consistently over-aged Coho Salmon from these systems prior to study initiation; visual assessment of known-age scale patterns now guides age determination to improve accuracy. Recent improvements in computer software have allowed these known-age smolt scales to be digitized then overlaid with estimates of circuli distances and freshwater age zones. Analysis of circuli measurements and smolt length was performed using Quadratic Discriminate Analysis to predict freshwater smolt ages and evaluated using the known ages. Model results show a high accuracy (>90%) for both stocks. Future use of this model can improve ageing performance and automate ageing processes, allowing for more effective management strategies of wild salmon populations.
09:40AM Break
1:10PM Evaluation of Dorsal Fin Rays and Spines As a Non-Lethal Ageing Method for Goliath Grouper Epinephelus Itajara
  Jessica Carroll, Angela Collins, Robert Ellis, Debra J. Murie
Atlantic Goliath Grouper Epinephelus itajara is the largest grouper in the western North Atlantic, and it exhibits life history characteristics that make it particularly susceptible to fishing pressure. In 1990 a harvest moratorium for Goliath Grouper in US waters was enacted, which created a data-poor environment from which to assess the stock status. Biological data, particularly fish ages, are needed to estimate population parameters for stock assessments. Otoliths, the typical structure processed for age determination, are unavailable from Goliath Grouper because of their protected status. Structures that can be obtained non-lethally, such as dorsal fin rays or spines, may provide a viable alternative for ageing. The Florida Fish and Wildlife Conservation Commission (FWC) has been collecting incidental Goliath Grouper samples from mortality events since 2006. Corresponding otolith, dorsal fin ray and dorsal spine samples from 77 fish were compared to determine the accuracy of these alternative ageing structures. The fish in this dataset range in age from 2–35 years (otolith age), and in size from 566–2244 mm TL. This research will inform biological sampling methodology for Goliath Grouper ageing structures and could directly impact the stock assessment, and potentially, the determination of recovery of the species.
1:30PM Utility of Otoliths, Scales, Fin Rays, and Opercles in Estimating the Age Structure of a Population of Blue Suckers
  Dakota Radford, Cassi Moody-Carpenter, Robert E. Colombo
Blue Suckers (Cycleptus elongatus) are distributed throughout the Mississippi-Missouri watershed. Of the twenty-three states they have occurred in they are listed as extirpated from one, endangered in one, threatened in four, and a species of concern in seven. The difficulty in sampling Blue Suckers, combined with their low monetary value in modern fisheries, has resulted in a shortage of research addressing this native species. The lack of research has limited conservation efforts at the state and federal level. We aim to inform Blue Sucker research and conservation by comparing the ease, associated mortality, and precision between four hard structures (otoliths, scales, pectoral fin rays, and opercles) used in estimating specimen age. Our comparison of aging structures is based on Blue Suckers collected in 2018 from an un-impounded Midwestern river (n=68). Specimens ranged in total length from 275-679 mm (average TL = 609.5 mm), with a conspicuous absence of juvenile samples. The age-structure, mortality rate, maximum length, and growth curve for this population will be compared to published demographics of other Blue Sucker populations. Ultimately, the demographic assessment of this population will augment the growing body of research addressing Blue Suckers and their status.
1:50PM On the Age and Growth of Deep-Pelagic Fishes, with Case Studies of the Top Predators Omosudis lowii, Stomias affinis, and Chauliodus sloani
  Natalie Slayden, Tracey Sutton
Deep-pelagic fishes provide important ecosystem services, such as carbon sequestration via the biological pump and prey provisioning for species targeted by fisheries (e.g., tuna, billfishes) and federally protected species (e.g., toothed cetaceans, seabirds). These services are becoming increasingly appreciated, even as mesopelagic fisheries are becoming of interest as coastal fisheries have become overexploited. In addition to emerging fisheries, climate change, ocean acidification, and seabed mining threaten deep-pelagic fishes. With increasing threats, age and growth information on deep-pelagic fishes is critical for management and conservation. The majority of age and growth studies to date have focused on the family Myctophidae (lanternfishes) due to their presumed importance in food chains; most other taxa remain relatively uninvestigated. In order to address these information gaps, age estimations and otolith microincrement descriptions linked to life histories will be presented on the top-predator fish species Omosudis lowii, Stomias affinis, and Chauliodus sloani. These fishes were collected from the northern Gulf of Mexico during seven research cruises from 2010–2011 (Offshore Nekton Sampling and Analysis Program) and during six research cruises from 2015–2018 (DEEPEND Consortium). Incorporating lifespan and growth rate estimations into ecosystem models provides critical data needed to manage and conserve burgeoning oceanic fisheries.
2:10PM Preliminary Analysis of Tripletail (Lobotes surinamensis) Age and Growth in the North-Central Gulf of Mexico
  Amanda Jefferson, Matthew Jargowsky, Meagan Schrandt, Pearce Cooper, Sean Powers, John Dindo, Marcus Drymon
Tripletail (Lobotes surinamensis) are migratory fish occupying tropical and subtropical waters worldwide. In the Western Atlantic Ocean and Gulf of Mexico, tripletail are increasingly targeted by recreational anglers. Previous age and growth studies have drawn conflicting conclusions concerning the use of tripletail otoliths for aging. The most recent Gulf of Mexico tripletail age and growth study used samples collected two decades ago; moreover, Gulf of Mexico tripletail age and growth has never been modeled. Therefore, this study aims to 1) evaluate first dorsal spines and otoliths as aging structures and 2) model Gulf of Mexico tripletail age and growth. From 2012 to 2018, tripletail (n = 208) were collected from the north-central Gulf of Mexico via hook-and-line. The first dorsal spine and both otoliths were extracted from each fish for aging. Tripletail ranged in size from 403–780 mm total length, with females significantly larger than males (D = 0.18, p = 0.02). The M:F ratio was 0.64:1 and significantly differed from a 1:1 ratio (X2 = 9.78, df = 1, p < 0.01). Findings from this study will inform management and help ensure the sustainability of Gulf of Mexico tripletail despite increased popularity among, and pressure from, recreational anglers.
2:30PM Age and Growth of Yellowfin Tuna (Thunnus albacares) from the Northwest Atlantic and Gulf of Mexico
  Ashley Pacicco, Robert Allman, Erik Lang, Brett Falterman, Debra J. Murie
Biological information derived from direct ageing methods is limited for Yellowfin Tuna Thunnus albacares. During 2004-2017, a total of 3,223 sagittal otoliths were collected from fishery-dependent and fishery-independent sources in the Gulf of Mexico (n=3,055) and the U.S. Atlantic (n=168). Yellowfin Tuna lengths ranged from 609 -1981 mm curved fork length (CFL). Age was determined by counting opaque zones in transversely sectioned sagittal otoliths. Ages ranged from 1 to 18 years, with 95% age 5 and younger. Fish 10-18 years old made up 2% of ages and were older than those reported from previous studies. The growth model with the most parsimonious fit to the age data was the Gompertz (L∞ =1606, Gi=0.4, t0=-0.11), followed by the logistic (L∞ =1580, Gi=0.5, t0=0.7) and the von Bertalanffy (L∞ 1647, k=0.29 t0=-1.44), suggesting that yellowfin tuna have indeterminate growth. Male and female growth curves were significantly different for all three candidate models (P≤0.001), with males obtaining a greater size than females which is consistent with previous studies. Increased sampling of Yellowfin Tuna from the pelagic longline fishery is needed throughout the northwest Atlantic to better represent growth of larger fish targeted by that fishing sector.
2:50PM Refreshment Break

Organizers: Jeffrey K. Fryer, Beverly Agler, Carlos Camacho, Timothy Copeland, Micah Davison, Lorna Wilson

Location: Reno-Sparks CC Date: October 3, 2019 Time: 8:00 am - 5:00 pm