Understanding climate impacts on the Maine coastal fish and invertebrate community through synthesis of the Maine-New Hampshire Inshore Trawl Survey

Lisa Kerr ¹ , Kathy Mills ¹, Riley Young Morse ¹ , Rebecca Peters ² , Andrew Allyn ¹, Jerelle Jesse ¹, Ashley Weston ¹

¹ Gulf of Maine Research Institute
350 Commercial Street
Portland, ME 04101

² Maine Department of Marine Resources
194 McKown Point Road
West Boothbay Harbor, ME 04575

Funding provided by Maine Sea Grant

Project Description

The overarching goal of this research is to synthesize data collected through the Maine-New Hampshire Inshore Trawl Survey to understand how climate change, fishing, and other environmental drivers are impacting key fish and invertebrate communities in coastal Maine waters.

The ME-NH Inshore Trawl Survey samples in 5 Regions and 4 depth strata from the MA-NH border to the ME-Canada border.

The ME-NH Inshore Trawl Survey can be compared to the MADMF Inshore Trawl Survey and NEFSC Bottom Trawl Survey which provide larger spatial coverage and duration.

Analysis

Objective 1: Analyze changes in biodiversity in space and time and evaluate associations with environmental factors and fishing

Biodiversity metrics

The ME-NH Inshore Trawl Survey (2000-2017) and NEFSC Bottom Trawl Survey (1963-2017) average fall biodiversity indices

Generalized Additive Mixed Models

ME-NH Inshore Trawl Survey and NEFSC GOM/GB Bottom Trawl Survey fall GAMMs with FVCOM data

ME-NH Inshore Trawl Survey and NEFSC GOM/GB Bottom Trawl Survey GAMMs: Bottom temperature

Objective 2: Identify species groups and assess changes in habitat suitability if functional groups and communities in space and time

Non-metric Multidimensional Scaling

ME-NH Inshore Trawl Survey functional group NMDS for spring and fall

ME-NH Inshore Trawl Survey top species NMDS for spring and fall

Analysis of variance

ME-NH Inshore Trawl Survey analysis of variance for regions and year blocks

Environmental relationships

ME-NH Inshore Trawl Survey linear and non-linear correlations of NMDS with environmental factors

Objective 3: Analyze joint distribution of key predator-prey species within the community, with a particular focus on lobster and cod

Vector Autoregressive Spatio-Temporal models

Schoener’s D overlap index for lobster and predators calculated from occurence stage predictions of single species VAST models and AB ratio and Schoener’s D overlap index for lobster and predators calculated from density predictions of single species VAST models.

Predicted log density of lobster and cod from fitted single species VAST models and gridded GLORYsv12.1 environmnetal data

Spatio-temporal correlations for species occurence from the VAST joint species distribution model

Objective 4: Evaluate how ecosystem changes align with shifts in diversity and composition of fishery landings over time in ports along Maine’s coastline

Biodiversity metrics

ME landings and ME-NH Inshore Trawl Survey average biodiversity indices

Functional groups

ME landings and ME-NH Inshore Trawl Survey functional group proportions

Correlation analysis

ME landings and ME-NH Inshore Trawl Survey correlation matrix for biodiversity indices

Conclusions

• Communities are changing over time in Maine waters and environmental factors are playing a key role, potentially changing predator-prey dynamics
• In general, species richness and average taxonomic distinctness are increasing, while evenness is decreasing indicating that taxonomically distinct species are emerging in a disproportionate way
• Temperature is a key driver for changes in indices.
• Maine inshore waters align well with the offshore signal for biodiversity indices and environmental drivers
• There is a decadal shift in Maine community structure indicated by NMDS
• Functional groups show an increase in benthivores driven by American lobster. Recent years show an increase in piscivores driven by hake species and a decrease in planktivores driven by Atlantic herring.
• There is a decline in overlap between lobster and cod as lobster suitable habitat has increased with declines in cod suitable habitat
• Interactions likely increased between lobster and other potential predator species, including skate and sculpin
• Maine landings have a smaller proportion of piscivores than the ME-NH Inshore Trawl Survey
• There is a benefit to using shorter time series surveys when put in context with surveys of larger spatial coverage and duration
  
  
• see tabs for more indepth analysis and figures
  
  

Contact:

Jerelle Jesse (jjesse@gmri.org)