Coastal Bays Fish Index For Report Card Image or Graphic Fisheries - - PowerPoint PPT Presentation

Coastal Bays Fish Index For Report Card

1

Fisheries Indicators for the Maryland Coastal Bays 6/02/10

Image or Graphic

Coastal Bays Fish Index For Report Card

2

• The report card website

(http://www.mdcoastalbays.org/content/ docs/Report%20Card.pdf) lists the following undeveloped fisheries indicators:

– finfish – blue crab – oysters

Coastal Bays Fish Index For Report Card

3

Fisheries Coastal Program has been asked to provide an index of fisheries resources that can be used as an indictor to grade the Coastal Bays.

• 1. Forage Index
• 2. Flounder Index
• 3. Indices suggested in the literature

Coastal Bays Fish Index For Report Card

4

• Abundance of forage species was

examined using a forage index. – Log mean CPUE of four forage species (Atlantic menhaden, spot, Atlantic silverside and bay anchovy). – These species are forage for both juvenile and adult game fish and may serve as indicators of habitat changes.

Coastal Bays Fish Index For Report Card

5

Fish forage index* for seine, Maryland Coastal Bays. *species:

Atlantic menhaden, spot, Atlantic silverside, and bay anchovy.

2 4 6 8 10 12 1972 1975 1978 1981 1984 1987 1990 1993 1996 1999 2002 YEAR

log-mean CPUE

Coastal Bays Fish Index For Report Card

6

Forage Index not used in report card because:

• Driven by spot abundance.
• Atlantic silversides and Atlantic menhaden prefer

shallower water while bay anchovy and spot prefer deeper water. The index was either a seine or trawl index, missing one or the other abundance component.

• Spot tend to be very cyclical in abundance.
• Bay anchovy, Atlantic menhaden, and Atlantic

silverside recruitment processes are little understood. We don’t know how variable the recruitment of these species are.

• Distribution of these species is variable throughout the

bays.

Coastal Bays Fish Index For Report Card

7

Summer Flounder as an Indicator

Image or Graphic

Coastal Bays Fish Index For Report Card

8

Reasons for Using Summer Flounder as an Indicator Species

• Summer flounder are caught at most sites and most months of the
• year. They have one of the most even distributions of the Coastal Bays
• f any species we study.
• Summer flounder are a widely recognized species and have commercial

and recreational value to the users of the coastal bays resources. Summer flounder make a great ‘Poster Child’ for an indicator species.

• Recruitment on a coastal scale is the most consistent of any species we
• study. It varies less from year to year than any other species we have
• studied. We know a lot about the recruitment variability of this species.
• We are central in the range of the species and they are abundant in the

Coastal Bays.

• A good index value will often translate into good fishing several years

down the road, making the value in the index something that people can actually see measurable results from.

Coastal Bays Fish Index For Report Card

9

Spawning Stock Biomass (SSB) and Recruitment (R)

10,000 20,000 30,000 40,000 50,000 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 Year

SSB (mt)

20,000 40,000 60,000 80,000 100,000

R (age 0, 000s)

R SSB

Coastal Bays Fish Index For Report Card

10

• Summer flounder will avoid a site if habitat quality is compromised

at that location, reducing the index value.

• A healthy population will result in a wide dispersion of juvenile

summer flounder in the bays and a high index value.

• Better indicator of habitat quality than just an abundance index.

While sensitive to fluctuations in the stock status, it is less sensitive than a pure abundance estimate

• Retrospective analysis of recent data indicates that while the

stock has continued to improve (SSB) the index plateaus.

• It reflects the coastal stock abundance which is critical to local

health of the population. Closes the loop in the association of local fish populations to coastal stocks.

• Easy to understand and translate to the general public.

Reasons to Use Percentage of Sites with Summer Flounder as Index

Coastal Bays Fish Index For Report Card

11

Coastal Bays Fish Index For Report Card

12

10 20 30 40 50 60 70 80 90 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 YEAR PERCENTAGE TRAWLS WITH SUMMER FLOUNDER

Coastal Bays Fish Index For Report Card

13

Coastal Bays Report Card Summer Flounder Index

• The Maryland Coast Bays Finfish Study does 20 trawls per month at fixed

sites, every month April through October for a total of 140 sites per year.

• The index is the percentage of sites that summer flounder are found in a

given year.

• A grade would be applied based on the percentage of sites that summer

flounder were captured. 70 and above = A 60-69.9 = B 50-50.9 = C 40-40.9 = D Below 40 = F

Coastal Bays Fish Index For Report Card

14

Another Index option:

– Index of Biotic Integrity (IBI)

• Consistent with the Chesapeake Bay Report Card

and other components of the Coastal Bays Report Card.

Coastal Bays Fish Index For Report Card

15

Linder, Cecelia C., James Casey, and Stephen J. Jordan. 1996 Ecological Integrity of Maryland’s coastal bays: effects of water quality, physical habitat, and land use characteristics.

– Objectives:

• Develop an IBI for the coastal bays.
• Apply the database to examine long term

changes in ecosystem integrity (since 1972) and how these changes may relate to anthropogenic factors.

Coastal Bays Fish Index For Report Card

16

Linder, Cecelia C., James Casey, and Stephen J. Jordan

• Objective: Apply the database, IBI, and

habitat assessments to map and interpret ecosystem integrity for the coastal bays in context of impacts from urbanization, water quality degradation, and habitat disturbance and destruction.

Coastal Bays Fish Index For Report Card

17

Linder, Cecelia C., James Casey, and Stephen J. Jordan

• IBI Metrics

– Total number of species, – number of species representing 90% of catch, – proportion of planktivores, – proportion of benthivores, – proportion of carnivores, – abundance of estuarine spawners, – abundance of marine spawners, – total number of fish less menhaden catch, – total number of blue crabs

Coastal Bays Fish Index For Report Card

18

Linder, Cecelia C., James Casey, and Stephen J. Jordan

• Analyses

– Calculated IBI per site, per month – Correlations of IBI to: chlorophyll a, total dissolved nitrogen, total dissolved phosphorus, bottom type. – Cluster analysis used to describe certain profiles of mean metric values and to rank clusters according to levels of biological integrity.

Coastal Bays Fish Index For Report Card

19

Linder, Cecelia C., James Casey, and Stephen J. Jordan

• Outcomes

– At the time, correlation analysis between IBI score and anthropogenic impacts limited by lack of water quality and habitat data. – More work was need on the fish habitat assessment, such as distance from shore and amount of structure.

Coastal Bays Fish Index For Report Card

20

Linder, Cecelia C., James Casey, and Stephen J. Jordan

• Outcomes

– No significant decrease in IBI score, but CPUE was declining. – Some species poorly sampled by trawl or beach seine.

Coastal Bays Fish Index For Report Card

21

Deegan, Linda A., et al. 1997. Development and validation of an Estuarine Biotic Integrity

• Index. Estuaries 20, No. 3: 601-617.
• Objective: test hypothesis on how estuarine

fish assemblages respond to habitat degradation & integrated those responses into an overall index.

Coastal Bays Fish Index For Report Card

22

Deegan, Linda A., et al.

• EBI Metrics – 15 tested & selected 8:

– total # of species – Dominance – fish abundance – # of nursery species – # of estuarine spawning species – # of resident species – proportion of benthic-associated fishes – proportion abnormal or diseased

Coastal Bays Fish Index For Report Card

23

Deegan, Linda A., et al.

• Outcomes

– Anthropogenic stress severely alters the function of SAV as habitat for higher trophic levels long before the plants disappear. – High diversity & abundance of fish in estuarine ecosystems are due to the physical structure

• f vascular plants that protect YOY from

predation, the abundance of food, and a suitable chemical environment. These attributes are three important indicators of the quality of estuarine conditions for fish.

Coastal Bays Fish Index For Report Card

24

Deegan, Linda A., et al.

• Outcomes

– EBI is a useful indicator of estuarine ecosystem status because it reflects the relationship between anthropogenic alterations in estuarine ecosystems and the status of higher trophic levels.

Coastal Bays Fish Index For Report Card

25

Other Fisheries Components for the Coastal Bays Report Card

Blue Crabs – An index similar to the one proposed by Steve could be worked

• n.

Oysters – Not a suitable indicator because of disease.

Coastal Bays Fish Index For Report Card

26

• Forage Index is not suitable for use in

the report card

• Summer Flounder Index would be clear,

understandable, and relatable.

• Other, more complicated options exist

– Would need immediate guidance from STAC to have product by 2011

• What is the timeline for index to be

complete?