2016 SoE Marine Chapter - State and Trends - Mesopelagic fish species

The Marine chapter of the 2016 State of the Environment (SoE) report incorporates multiple expert templates developed from streams of marine data. This metadata record describes the Expert Assessment "The state and trends of quality of species and groups – mesopelagic fish species". The full Expert Assessment, including figures and tables (where provided), is attached to this record. Where available, the Data Stream(s) used to generate this Expert Assessment are accessible through the "On-line Resources" section of this record.

DESCRIPTION OF ECOLOGICAL SPECIES/COMMUNITY FOR EXPERT ASSESSMENT
Mesopeolagic fish species (200 to 1000 m depths) of the Australian region are thought to be in very good condition as there is limited direct impact by human activities (e.g. no targeted commercial fishing, and limited seismic surveys). Therefore factors affecting the mesopelagic fishes and their habitats will most likely be due to overall changes in environmental conditions associated with climate change and variability influencing factors such as primary production, ocean acidification and changing oxygen levels (Hobday and Pecl, 2014). This estimate of mesopelagic fish status and trend is uncertain due to the low amount of monitoring that is done, but monitoring has increased since the last assessment in 2011.
Monitoring of mesopelagic fishes has recently been included in Australia’s Integrated Marine Observing System (IMOS) through a bio-acoustics sub-facility in 2010 with one focus being the Tasman Sea (www.imos.org.au). Mesopelagic fishes are very diverse in Australian waters where in a recent field guide of the southern Tasman Sea 143 species in 43 families were identified (Flynn and Pogonoski, 2012). Using the IMOS bioacoustics Tasman Sea transect along 40oS there has been no detectable change in the annual acoustic index of mesopelagic fish biomass off the east coast of Tasmania between 2004 and 2013 (Kloser et al pers comms, www.imos.org.au). This region has a diverse range of fishes that have complex depth distributions and trophic interactions (Flynn and Kloser, 2012).
Ecosystem models and observational studies of mesopelagic fishes highlight their importance to ecosystem structure and function where they transfer energy to higher order predators such as commercial fish species in Australian waters (Fulton et al., 2005; Lehodey et al., 2010; Young et al., 2011). This is particularly important for Australia’s continental slope commercial species and other top predators for ecosystem based management (Smith et al., 2011). The importance of mesopelagic fishes to ecosystem services has been shown yet their biomass and production is uncertain with several recent net and acoustic estimates differing by 2 orders of magnitude in Tasman Sea Australian waters (Kloser et al., 2009; Irigoien et al., 2014). This difference is based on using different sampling gear and methods to interpret the data.
The outlook for mesopelagic fish in the Australian region is very good given the low direct impact of human activities (e.g. fishing) and increased monitoring through the IMOS bioacoustics program. Spatial and temporal shifts in mesopelagic fishes are expected to occur due to climate change and variability which will influence the distribution of their predators (Ridgway et al., 2008; Hobday and Pecl, 2014). To understand shifts in higher order predators and their ecological and human impact monitoring and ecosystem modelling of mesopelagic fish status and future trends is necessary.
DATA STREAM(S) USED IN EXPERT ASSESSMENT
Data from the IMOS bio-acoustics sub-facility, data from surveys along a transect line in the Tasman Sea repeated across 2004-2013.

2016 SOE ASSESSMENT SUMMARY [see attached Expert Assessment for full details]
• 2016 •
Assessment grade: Very good
Assessment trend: Stable
Confidence grade: Limited evidence or limited consensus
Confidence trend: Limited evidence or limited consensus
Comparability: Grade and trend are comparable to the 2011 assessment
• 2011 •
Assessment grade: Very good
Assessment trend: Stable
Confidence grade: Limited evidence or limited consensus
Confidence trend: Limited evidence or limited consensus

CHANGES SINCE 2011 SOE ASSESSMENT
N/A

Tags: community structure, expert assessment, mesopelagic
Organization: Australian Ocean Data Network