DOI: 10.5061/dryad.9w0vt4bph
title: Estimating enhanced fish production on restored shellfish reefs using automated data collection from underwater videos

description: Shellfish reefs across the world have been heavily degraded by mechanical
 harvesting, disease, and declining water quality. In southern Australia,
 where substantial losses have occurred, Government and non-government
 efforts to restore functioning reefs are now underway with a strong focus
 on enhancing fish productivity. However, the capacity of these restored
 reefs to enhance fish production remains unknown, hampering estimates of
 return on investment. We quantify the density differences of
 newly-recruited juvenile fish and other nekton on these restored reefs,
 relative to those on unrestored, unstructured habitat. Fish were surveyed
 at three paired reef-unstructured locations using 169 unbaited stereo
 video deployments during three periods over 12 months (2022–2023). We used
 automation software, FishID, to automatically identify, size, and count
 fish in videos. We subsequently applied known growth and mortality
 parameters to model enhancement of fish productivity.  Sixteen
 species occurred as new recruits, with all but two found at higher
 densities on reefs than in an unstructured habitat. Enhancement of fish
 production from subtidal restored shellfish reefs from a single year’s
 cohort is estimated to be, on average, 6,186 kg.ha-1.yr-1 (SD 1,802) after
 enough time has elapsed for all species to have matured. Species harvested
 commercially or recreationally contributed 98% of that production (6,083
 kg.ha-1.yr-1, SD 1,797).  Enhancement varied greatly among
 locations, ranging from 12,738 kg.ha-1.yr-1 (SD 2,894), which is the
 highest yet recorded anywhere, to 1.4 kg.ha-1.yr-1 (SD 0.9).  The
 lack of juvenile fish at the location with the lowest estimated
 enhancement might be explained by the impact of overfishing on recruitment
 of key species, or by an abundance of alternative habitat for juvenile
 fish.  Synthesis and applications. The combination of underwater
 videos with automated data extraction provides a reliable, cost-effective
 method for surveying fish on oyster reefs. By quantifying enhanced fish
 productivity on reefs, we provide estimates that will underpin
 calculations of ecological, social, and financial benefits, supporting the
 business case for scaling-up restoration efforts.
description: Stereo underwater cameras in two habitats: restored
 oyster reefs and unrestored, unstructured control habitat
 Three survey periods over 12 months FishID
 software automatically extracts data from videos to identify all fish (and
 cephalopods and crabs) Fish sizes measured from
 synchronised stereo imagery, only juvenile fish counted
 Area of camera field of view calculated
 Counts of juvenile fish converted to densities per unit area,
 for each habitat for each survey period, for each species
description: # Estimating enhanced fish production on restored shellfish reefs using
 automated data collection from underwater videos
 Experimental purpose These
 data were collected to determine the difference in density of juvenile
 fish on restored oyster reefs relative to unrestored, unstructured control
 habitat at three locations in southern Australia. Stereo underwater
 cameras in two habitats: restored oyster reefs and unrestored,
 unstructured control habitat 1. Three survey periods over 12 months 2.
 Data automatically extracted using FishID software
 3. Fish identified, sized, and counts of
 juvenile fish made 4. Area of camera field of view calculated, counts
 converted to densities per unit area Dataset contents * Density of
 juvenile fish per survey period per habitat per location for every species
 ## Description of the data and file structure 1. Species name (names as
 per Table 3 in associated published paper) 2. Survey period (first,
 second, third) 3. Location (Dromana, Glenelg, Margaret) 4. Habitat (reef,
 unstructured) 5. Deployment (individual deployment number) 6. Fish density
 (per 100m2) ##