CHESFIMS 2003 July Shoal Survey Report
Survey Dates: 7 July 2003 – 25 July 2003
Boat Used: 20.0’ Maycraft with 130 HP engine
MD DNR Co-Principal Investigator: Alexei Sharov
Chief Scientist: Brandon Muffley
Phone Number: (410) 260-8284
E-mail:
Participating Scientists:
1. B. Muffley – MD DNR6. P. Genovese – MD-DNR
2. T. Hershberger – MD-DNR7. T. Jarzynski – MD-DNR
3. B. Murphy – UMD-CBL8. A. McCauley – MD-DNR (intern)
4. B. Kaminski – UMD-CBL (intern)9. M. Topolski – MD-DNR
5. S. Moulds - ACB
Objectives:Obtain data on the relative abundance and biological characteristics of the bentho-pelagic fish community in the extensive shoal habitats (< 5m depth) in the Maryland portion of Chesapeake Bay. Collect and preserve a sub-sample of catch for dietary analysis.
Area of Operation: From the MD/VA line (approximately 37.5ºN) to just south of the Aberdeen Proving Grounds (39.15ºN).
Type of Operations: Conducted 6-minute bottom-water trawls and recorded a number of biological, environmental and water quality variables at 123 stations in 9 different strata in Chesapeake Bay (Table 1, Figure 1).
Data / Specimens Collected: Collected 9,303 fish and crabs (over 112 kg) from 31 different taxonomic categories (Table 1). Preserved (EtOH) samples from approximately 50 stations where targeted species were present in the catch. Environmental and water quality data recorded from each station.
Damage to Gear: While sampling the Patapsco stratum on July 24, 2003 the trawl hung
up on some unknown object. With some work, we were able to free
the trawl from the snag, but the shackles and pins on the trawl doors
were severely damaged. We replaced the damaged doors with new
trawl doors of the same shape and design. We also plan to replace
the trawl itself for the fall survey. We have been using the same
trawl for the past 3 surveys and there is extensive wear and tear on
the trawl and liner, plus patchwork (i.e. repairs) on the trawl is
not holding any longer.
Also, the YSI meter did not work on several occasions: 7/14/03 – Little Choptank (some information), 7/15/03 – Choptank, and 7/21/03 – Calvert Cliffs, so we were unable to collect water quality data on those days.
Figure 1. ChesFIMS 2003 July shoal survey station locations.
Cruise Summary:
We started the shoal portion of the survey on Monday, July 7 and finished on Friday, July 25, 2003. This time period included 15 working days, 13 of which were spent sampling. The strata were not sampled in any pre-determined or systematic order but were sampled on any particular day based upon weather conditions and crew availability. Once at a particular location, the order in which the stations were sampled was not pre-determined but based upon weather conditions and tide state.
Overall, the July survey was successful and all objectives were met or exceeded. Based upon survey design (random with allocation proportional to strata size), it was determined that 112 stations were required to be sampled and we were able to sample 123 stations (Table 1), one less than in May 2003. In total, 9,303 fish and crabs were caught with a total weight of approximately 112 kg (Table 1). Unlike the broadscale survey, this was our highest total catch to date. We caught fish from 116 of the 123 stations sampled (94%), our highest percentage of non-zero catches (i.e. lowest percentage of zero catches), and 4 of the 7 zero catches were from Calvert Cliffs. Accounting for all species and all strata, the overall catch tow-1 was 75.6 112.6 fish (mean SD, range 0 – 917). The July 2003 catch rate was over 3 times as great as July 2002 (21.94 ± 27.29, mean ± SD) and similar to July 2001 (81.06 ± 122.52). The two northernmost strata, Patapsco and Chester, had the highest catch rates (mean 224.3 ± 266.5 SD, 132.3 ± 92.8, respectively), while Calvert Cliffs and Little Choptank strata, the same area latitudinaly, had the lowest catch rates (mean 18.5 ± 32.6 SD, 20.4 ± 18.6, respectively) (Figure 2). Both, the total number of fish caught (9,303) and total biomass (112 kg), were the highest July values for the shoal survey (2001 – 8,754 fish, 41 kg, 2002 – 2,473 fish, 66 kg). The Patapsco and Tangier Sound combined, comprised almost 74% of the total biomass for the entire survey (Table 1). The total number of different species caught (31), and the number of species caught tow-1 (Figure 3) for the July survey was also the highest among the three July surveys (2001 – 22 species, 2002 – 27 species).
For the second consecutive survey, bay anchovy (Anchoa mitchilli) was not the most abundant fish encountered. However, anchovy abundance was considerably higher than this past May’s record lows and was also higher than July 2002, but still remains well below abundance estimates from 2001 (Figure 4). White perch (Morone americana) was the most abundant species, comprised almost 30% of the total catch, and was found in all strata except Pocomoke Sound and Little Choptank. Striped bass (Morone saxatilis) was the third most abundant species and was found in all strata except Tangier and Pocomoke Sound. The high abundance of striped bass can be attributed to the large catches of YOY, seen for the first time in the shoal survey (Figure 4). White perch, striped bass, and bay anchovy were all common in the most northern strata. While weakfish (Cynoscion regalis), spot (Leiostomus xanthurus), and blue crabs (Callinectes sapidus) dominated the catch in the southern strata. Also unlike the broadcale survey, striped anchovy (Anchoa hepsetus) was commonly encountered this survey, particularly in many of the lower eastern shore strata. A summary of the biological characteristics of all species caught during July is provided in Table 2.
At the end of each trawl, surface and bottom YSI measurements (temp, DO, and salinity) and secchi disk readings were taken at every station. The YSI meter was not working on the days we sampled the Choptank (7/15/03) and Calvert Cliffs (7/21/03), so we do not have readings for those two strata, and we only have a few readings from the Little Choptank (7/14/03). Water temperature was relatively uniform across all strata and between the surface (mean 27.3 C, range 24.0 – 31.5) and bottom (mean 26.9 C, range 24.3 – 30.0). Salinities ranged from a mean surface low of 4.1/ and mean bottom low of 4.6/ in the Patapsco stratum, to a mean surface high of 12.7/ and mean bottom high of 12.9/ in Pocomoke Sound. July 2003 salinities were, on average, 6 ppt lower than salinities in July 2002. For example, mean surface salinity in Pocomoke Sound was 12.7/ in 2003, compared to 19.8/ in 2002. DO readings (mg/L) were not only variable between strata, but even within each stratum. The mean surface DO for all strata was 6.91 mg/L, with a high of 9.6 mg/L in Patapsco and a low of 4.9 mg/L in Tangier Sound. The mean bottom DO was only slightly lower than the mean surface readings, 6.1 mg/L, and there were only a few locations, particularly in the Little Choptank, where DO levels fell below 4.0 mg/L. The mean water clarity depth for all stations was 0.99 m (range 0.39 – 1.92m), which was lower than May readings (mean 1.22 m). As in May, Calvert Cliffs had the highest water clarity reading with a mean of 1.47m (exact same as in May), and the Patapsco stratum had the poorest water clarity with a mean depth of 0.53m.
Sampling Dates / Stratum / # of Trawls / # of Fish Caught / Total Weight (kg) / # of SpeciesChester / 9 / 1191 / 4.81 / 6
Eastern Bay / 9 / 681 / 1.58 / 7
Choptank / 12 / 789 / 6.02 / 15
Little Choptank / 10 / 204 / 3.58 / 13
7/7/03 – 7/25/03 / Tangier Sound / 34 / 2908 / 28.26 / 23
Pocomoke Sound / 21 / 624 / 6.27 / 18
Patapsco / 9 / 2019 / 54.75 / 9
Severn/South / 9 / 702 / 5.52 / 8
Calvert Cliffs / 10 / 185 / 1.78 / 15
Total / 123 / 9303 / 112.57 / 31
Table 1. Summary of July 2003 survey sampling intensity and catch results.
Common Name / Total N / Total Weight (g) / Mean Length (mm) / S.D. / Range (mm)Alewife Herring / 22 / 100.5 / 75.0 / 20.8 / 38 - 107
American Eel / 4 / 432.0 / 349.8 / 112.0 / 238 - 504
Atlantic Menhaden / 1 / 1.0 / 55.0 / ***** / *****
Atlantic Silverside / 141 / 118.5 / 48.3 / 10.3 / 25 - 72
Bay Anchovy / 2404 / 1613.5 / 39.3 / 17.7 / 18 - 91
Black Sea Bass / 7 / 167.0 / 121.4 / 11.2 / 135
Blackcheek Tounguefish / 1 / 10.0 / 106.0 / ***** / *****
Blue Crab / 437 / 26007.0 / 90.2 / 33.1 / 25 - 168
Channel Catfish / 1 / ***** / 40.0 / ***** / *****
Croaker / 14 / 894.0 / 94.9 / 112.0 / 19 - 308
Fringed Flounder / 1 / 9.0 / 90.0 / ***** / *****
Hogchoker / 234 / 4343.0 / 93.8 / 21.6 / 50 - 170
Horseshoe Crab / 4 / ***** / ***** / ***** / *****
Lizardfish / 23 / 28.0 / 60.1 / 15.1 / 39 - 102
Naked Goby / 7 / ***** / 26.3 / 11.9 / 17 - 47
Northern Kingfish / 2 / 2.0 / 45.0 / 14.1 / 35 - 55
Northern Pipefish / 37 / 6.0 / 108.7 / 33.7 / 50 - 205
Northern Puffer / 7 / 6.0 / 36.7 / 9.5 / 25 - 49
Northern Sea Robin / 174 / 1646.0 / 102.6 / 12.0 / 74 - 138
Oyster Toadfish / 18 / 2084.0 / 173.4 / 47.4 / 91 - 262
Skilletfish / 1 / ***** / 32.0 / ***** / *****
Spot / 336 / 6427.0 / 100.6 / 31.4 / 70 - 259
Striped Anchovy / 468 / 1645.0 / 75.4 / 5.5 / 53 - 95
Striped Bass / 1124 / 3021.5 / 61.6 / 19.9 / 25 - 270
Stripped Blenny / 1 / 2.0 / 72.0 / ***** / *****
Summer Flounder / 25 / 3713.0 / 207.1 / 96.3 / 117 - 460
Weakfish / 1095 / 1782.0 / 50.2 / 15.3 / 21 - 229
White Catfish / 1 / 160.0 / 230.0 / ***** / *****
White Perch / 2691 / 58371.5 / 88.5 / 68.4 / 23 - 253
Windowpane / 5 / 120.0 / 105.6 / 45.7 / 55 - 174
Winter Flounder / 17 / 75.0 / 73.2 / 9.3 / 60 - 91
Table 2. Biological characteristics of all species caught during the July 2003 survey.
Figure 2. Strata comparison of the overall (all species) catch tow-1 for the July 2003 sampling period.
Figure 3. Species diversity comparisons, measured as # of species tow-1, across survey years. (Note: Only those strata sampled in all 3 years shown here)
Figure 4. Yearly comparison of July catch rates (catch tow-1) for a few of the most common species found during the three survey years. 2001 – 108 trawls, 2002 – 113 trawls, 2003 – 123 trawls.