Effect of Ocean Warming Trends on Cod Spawning

Analyzing the GSC HMA and looking at large scale temperature related trends

Garrett Bellin

November 13, 2022

01 / 10

Initial Question

The Great South Chanel Habitat Management Area (GSC HMA)

Prohibits fishing on spawning grounds

Is this area outdated?

Management Area with clam dredge exemption zones shown.

Did the cod leave?

NOAA DisMAP (Spring)

Spawn Winter-Early spring

DisMAP - Distribution Mapping and Analysis Portal

Use this module to explore the aggregate change in location of marine species caught in a survey at a regional level. As species distributions respond to many environmental and biological factors, looking at changes at the community level, aggregating across all species or across species groups, allows for a more complete picture of the general trends in marine species distributions in a region.

https://apps-st.fisheries.noaa.gov

"Weight count per unit effort" or WTCPUE

Larger circle = Higher WTCPUE at survey Point

Smaller circle = Lower WTCPUE at survey point

Red dot = No cod found at survey point.

Note:

Management Zone has no Surveys

Red dots increase, yellow get smaller over time

Overall View

Coastal Northward Trend

Complete Cod absence in south

Clusters around Georges Bank and Gulf of Maine

Where did they go?

Lack of Cod Spawning Information

Information on where they like to spawn

More than temperature

Habitat Suitability Index Model based on these factors

Determine suitable areas for apprpriate management

Factor #1

Temperature

Multidimensional data, time and temperature (NetCDF)

Time slider by year 1974-2019

4-8 degrees Celsius Light Blue and Green Blue

Black dot size = Survey point WTCPUE quantity

White dots show absence of cod at survey point

Create suitability model by year - dynamic data

Can predict future based on suitability change over time

NOAA ROMS-GlORYS-PSY

Factor #2

Substrate Type

Substrate Type Layer USGS

USGS Open-File Report 2005-1001: References

Data in this publication are provided with geographic coordinates to allow the data to be integrated into a Geographic Information System (GIS). A GIS is defined as a system of hardware and software to support the display, manipulation, and analysis of spatial data for mapping and complex data solving.

https://woodshole.er.usgs.gov

Analysis run to rank substrates based on suitability.

Graph #1 is weighted by WTCPUE

Graph #2 is only Points

This chart shows density of cod distribution by substrate using weight count measures.

This chart shows density of cod distribution by substrate using sightings without weight count.

Factor #3

Bathymetry

We will use a similar approach with bathymetry

Shallower water = more nutrients and feeding oppurtunities

Quantatitive data ranges

Darker blue = deeper

Lighter blue = shallower

Didn't use WTCPUE in initial analysis

Bathymetry stats in our study area of cod distribution points

GEBCO Bathymetry data

Gridded bathymetry data (General Bathymetric Chart of the Oceans).

GEBCO's current gridded bathymetric data set, the GEBCO_2022 Grid, is a global terrain model for ocean and land, providing elevation data, in meters, on a 15 arc-second interval grid. It is accompanied by a Type Identifier (TID) Grid that gives information on the types of source data that the GEBCO_2022 Grid is based on.

https://www.gebco.net

Other Factors?

Distribution data - how far do cod travel from spawning sight?

Sea floor geomorphology - Esri Sea Floor Geomorhpology Map Service

El Niño and La Niña

Open to adding any factors

Next Steps

Weighting each factor

Ranking each variation

Suggest movement of outdated management areas

Broaden our horizon to other species

Fall "Dismap" data points

Policy Changes and Education

Final thoughts

GSC HMA is outdated

Northward cod movement poses ecological and economic threat

Overal decrease in suitable habitat

Final grant goal: To create a working suitability and prediction model for cod spawning suitability and template for use on other species.