Review of Shark Sanctuary policies
Describes the details of what shark sanctuaries are and are not, looking at the details of the geopolitical features of the countries and the policies implemented, as well as historic shark catches to understand potential impact to shark populations and markets, and recommends program evaluation.
The Role of the Tourism Industry
Juvenile shark microhabitats
Work with Dr. John Carlson at the NOAA Southeast Fisheries Science Center, Florida. Used existing data collected by John and his colleagues to map juvenile shark populations in bays in the northeast Gulf of Mexico and to use model to determine which habitat characteristics were influential in their distributions.
Economic Value of Sharks
Although studies that appraise the economic value of living resources are valuable, it is important fairly evaluate all sides of a resource and, instead of juxtaposing one industry against the other, in this case the fishing industry against the tourism industry, it is prudent not to ignore the fact that both industries are of global economic importance and rely on healthy shark populations.
Risks to manta rays
eManta was a crowd-sourced data project that assessed global manta ray populations. The findings of this study were influential for at least two countries in their decision to support the listing of manta rays on Appendix II of CITES in 2013.
103 million sharks killed per year
Evaluation of the global threat of sharks to fishing mortality – our best estimate, considering as many sources as we could find, was that 103 million sharks die annually and that this rate of mortality exceeds reproductive rates, which explains why we see declining trends. Immediately following this publication, where the findings were well aligned with numerous other studies from around the world, five sharks species were listed on Appendix II of CITES in 2013.
Chapman DD, Frisk MJ, Abercrombie DL, Safina C, Gruber SH, Babcock EA, Feldheim KA, Pikitch EK, Ward-Paige CA, Davis B, Kessel S, Heithaus M, Worm B (2013) Give shark sanctuaries a chance. Science. 339: 757.
Shark Sanctuaries may be difficult to enforce in the field, but made easier if all shark products are prohibited and fisheries agencies work with other national agencies (e.g., monitor exports)
Shark population recoveries
Shark Population Recovery Potential – Despite increased value and policies that aim to protect sharks, still only few examples showing increasing trends and none have yet recovered. Time and a combination of strong and dedicated management actions are required for success.
Thailand sharks & divers
Computer simulations of divers and sharks explored detection rates of the roving diver technique, used by recreational divers, across a range of fish densities and speeds, and found that roving divers have the potential to detect fish at very low densities compared to other survey techniques; Field interviews of divers, ranging from beginners to experts, immediately following a dive with sharks in the wild, found that inexperienced recreational divers detect and count elasmobranchs as well as experienced recreational divers; Semi-structured interviews of dive instructors were used to demonstrate the value of their recollections in terms of effort and their descriptions of spatial and temporal distributions of sharks in Thailand.
Marine animal recoveries
Lotze HK, Coll M, Magera AM, Ward-Paige CA, Airoldi L (2011) Recovery of marine animal populations and ecosystems. Trends in Ecology and Evolution. 26(11): 595-605. Figure 2 from this publication shown below.
Review of marine recoveries revealed how common recovery is, with its magnitude, timescale and major drivers. Reduction of human impacts, especially exploitation, habitat loss and pollution are essential. However, extent and possibility of recovery is determined by life-history characteristics and environmental conditions. Awareness, legal protection and enforcement of management plans were also influential.
UVC bias & biomass structure
Ward-Paige CA, Mills Flemming J, Lotze HK (2010) Overestimating fish counts by non-instantaneous visual censuses: consequences for population and community descriptions. PLoS ONE. 5(7): e11722. Figure 5 from this publication is shown below.
**Note: This is my most mis-cited paper, where most citations declare the bias as ‘recounting’, but there was no recounting since it was a simulation and fish were purposefully removed after detection. The idea here is that moving fish are infinitely more likely to enter a survey boundary during a census than stationary fish. The faster the fish moves, unless it’s just moving in small circles, the more likely it is to cross into a census area. Therefore, the density of faster moving fish, which are usually the largest and higher up the pyramid (e.g., sharks and jacks) are artificially inflated relative to the stationary fish, which tend to be smaller and lower down the pyramid (e.g., damselfish).
This study began because reviewers of another paper, understandably, would not accept guess-estimates of natural shark density. Instead, they called for published densities from remote areas to be used.
However, these published studies put apex predator densities at >100,000 individuals·km−2, and biomasses >4 tonnes·ha−1, well beyond our best guess or that of experts we discussed this with.
Previously written computer simulations of divers and sharks were then adapted to compare the difference between observed and actual densities of fish. Importantly, the investigation was of divers that use ‘non-instantaneous’ belt-transect or stationary-point-count techniques – that is, fish that entered the transect boundaries after the survey began were included. This is (was?) the most common UVC methodological technique at the time, which was based on my interviews with numerous scientific divers around the world. During these interviews, only one person described using a series of ‘instantaneous’ snapshots as they moved along the transect, thereby excluding fish that entered the transect after the survey began.
Using the results of the simulations, we assessed how fish speed and survey procedure (visibility, diver speed, survey time and dimensions) affect observed fish counts. Results indicate that the bias caused by fish speed alone is huge, while survey procedures had varying effects. Because the fastest fishes tend to be the largest, the bias would have significant implications on their biomass contribution. Therefore, caution is needed when describing abundance, biomass, and community structure based on non-instantaneous UVC, especially for highly mobile species such as sharks.
Caribbean shark populations
Ward-Paige CA, Mora C, Lotze HK, Pattengill-Semmens C, McClenachan L, Arias-Castro E, Myers RA (2010) Large-scale absence of sharks on reefs in the greater-Caribbean: a footprint of human pressures. PLoS ONE. 5(8): e11968.
Between 2008 and 2010, 76,340 underwater surveys carried out by trained divers, reported to REEF, were used to describe the shark populations compared to nearby human density. Sharks, with the exception of nurse sharks, occurred mainly in areas with very low human population or strong fishing regulations and marine conservation. Population viability analysis suggests that exploitation alone could explain the large-scale absence. The Bahamas was the exception – high sharks and humans – which was the impetus for implementing the Bahamas Shark Sanctuary in 2011.
Citizen science of yellow stingray
Between 2008 and 2010 83,940 dives collected by trained volunteer divers, and reported to REEF, were used to examine spatial and temporal trends of the most frequently sighted elasmobranch species in the greater-Caribbean, the yellow stingray (Urobatis jamaicensis). Despite being relatively common and listed as Least Concern on the IUCN Red List, little was known about the status of this species. In total, yellow stingrays were observed on 5,658 surveys (6.7% sighting frequency). This was my first analysis of the value of non-scientific divers for collecting data that can be used to understand population trends of otherwise poorly studied species.
Nutrients on coral reefs
Solutions to Stormwater Runoff – Presented at CGU-CMOS – 2016. VIEW PROGRAM
Can a stream that runs through an ‘industrial park’ – even if it IS shaped like a fish and connects to the ocean – function as well as a natural stream? This work assesses the impacts of stormwater runoff and in-stream barriers on coastal and aquatic ecosystems in Dartmouth, Nova Scotia – aka, “The City of Lakes” – where I call home. I am especially interested in evaluating the impact that watershed restoration ‘solution’ projects are having on downstream water quality, habitat health and fish populations.