Fish

The fish of Millbrook Marsh were most recently inventoried in August 1997 (Brooks et al. 1998). The streams were considered as 3 individual reaches when analyzing the fish communities. Thompson Run extended from the mouth at Slab Cabin Run, upstream to the bridge at Route 26. Lower Slab Cabin Run extended from the bridge at Puddintown Road, upstream to the confluence with Thompson Run and Upper Slab Cabin Run, from the confluence with Thompson Run, upstream to the bridge at Route 26.

Wild brown trout (Salmo trutta), rainbow trout (Oncorhynchus mykiss), white suckers (Catostomus commersoni), and slimy sculpins (Cottus cognatus) were found in both Thompson Run and Lower Slab Cabin Run (Table 6-9). Wild brown trout, white suckers, blacknosed dace (Rhinichthys atratulus), and creek chubs (Semotilus atromaculatus) were found in Upper Slab Cabin Run (Brooks et al. 1998). The Stream Survey Report of 1941 listed abundant "fish food minnows", brook trout, now missing, brown trout, rainbow trout, minnows, and suckers in Lower Slab Cabin Run and classified it as a "Brown Trout Stream." The same fish species were found in Thompson Run (Donley 1941). Station 3 of the PennDOT study was located in Upper Slab Cabin Run, and the fish species were inventoried in 1979 (PennDOT 1981). The fish found were golden shiner (Notemigonus erysoleucas), longnose dace (Rhinichthus cataractae), creek chub, white sucker, largemouth bass (Micropterus salmoides), and pumpkinseed sunfish (Lepomis gibbosus). These fish species are representative of warm water, despite the classification of Slab Cabin Run as a cold water stream.

For the 1997 inventory, density and biomass estimates were made for brown trout only since rainbow trout were not captured consistently in any of the 3 reaches (Table 6-11). Density and biomass estimates of brown trout were highest in Thompson Run (4800/ha, 423 kg/ha), followed by Lower Slab Cabin Run (983/ha, 106 kg/ha) and Upper Slab Cabin Run (761/ha, 106 kg/ha). Recruitment of young-of-the-year fish, those from 1997, was good in all 3 stream reaches, as evidenced by the first peak in length-frequency distribution of fish 139 mm and smaller. A gap in 1 year old fish 139-169 mm long indicates poor recruitment during 1996, most likely due to the severe flooding that occurred early that year.

The change in the fish population in Slab Cabin Run and Thompson Run includes a lowered species richness and a much higher proportion of Brown trout than in the past (Table 6-10). Pumpkinseed and Golden shiners have not been seen in either stream since 1979, in addition to the loss of Largemouth bass, Longnose dace and Goldfish. These fish species that have disappeared, though, are warm water fish. The whole of the Spring Creek watershed is designated at least Cold Water Fish, with some stream reaches High Quality CWF. The temperature criteria for CWF is the most stringent. Temperature change may not exceed more than 2° F (1.1° C) and the allowed temperatures range through the year from a maximum of 38° F (3.3° C) in January to a maximum of 66° F (18.8° C) in July and August The native Brook trout, a cold water fish, is not in any of the inventories, though it was throughout the Spring Creek watershed, including Millbrook Marsh, in the 1941. It is still found in streams throughout the watershed. Brown trout dominate both Slab Cabin Run and Thompson Run at this time, with a very large increase in population since 1989.

		1941		1979			1987	1989	1997
Species	Common Name	Lower Slab Cabin Run	Thompson Run	Upper Slab Cabin Run	Slab Cabin Run	Lower Slab Cabin Run	Thompson Run	Upper Slab Cabin Run	Thompson Run	Upper Slab Cabin Run	Lower Slab Cabin Run
	Minnows	*	*
Carassius auratus	Goldfish						*
Catostomus commersoni	White sucker	*sp.	*sp.	*	*	11	*	*	2	80	2
Cottus cognatus	Slimy sculpin					4	*		63	6	38
Micropterus salmoides	Largemouth bass			*	*		*
Notemigonus erysoleucas	Golden shiner				*
Oncorhynchus mykiss	Rainbow trout	*	*						13		3
Rhinichthys atratulus	Blacknose dace					1		*		10
Rhinichthys cataractae	Longnose dace			*	*			*
Salmo trutta	Brown trout	*	*			12	65	6	313	147	253
Salvelinus fontinalis	Brook trout	*	*
Semotilus atromaculatus	Creek chub			*	*	3	*			2
Lepomis gibbosus	Pumpkinseed			*	*
Total species		5	5	5	6	5	6	4	4	5	4

Brown Trout
	Thompson Run			Lower Slab Cabin Run			Upper Slab Cabin Run
Length Group (mm)	Total caught (N)	Mean Weight (g)	*gN (kg)**	Total caught (N)	Mean weight (g)	*gN (kg)**	Total caught (N)	Mean weight (g)	*gN (kg)**
60-69							4	0	0.00
70-79	8	4	0.16	3	4	0.02	13	4	0.09
80-89	39	7	1.38	20	7	0.26	22	7	0.26
90-99	40	14	2.83	33	14	0.84	17	14	0.41
100-109	51	16	4.13	22	16	0.64	10	16	0.27
110-119	38	18	3.46	5	18	0.16	1	18	0.03
120-129	11	20	1.11	2	-	-	1	-	-
130-139	4	25	0.51	0	0	0.00	0	0	0.00
140-149	0	0	0.00	0	0	0.00	1	0	0.00
150-159	1	41	0.21	1	40	0.07	0	41	0.00
160-169	0	0	0.00	0	0	0.00	1	-	-
170-179	2	57	0.58	6	62	0.68	1	60	0.10
180-189	7	75	2.66	5	72	0.66	2	75	0.26
190-199	8	81	3.30	5	78	0.71	4	82	0.56
200-209	11	98	5.45	11	94	1.89	3	93	0.48
210-219	11	110	6.15	17	104	3.23	3	105	0.54
220-229	17	126	10.88	14	115	2.94	6	125	1.28
230-239	10	148	7.50	11	128	2.57	3	135	0.69
240-249	7	159	5.62	16	153	4.46	7	104	1.25
250-259	6	192	5.82	14	164	4.19	8	188	2.56
260-269	3	215	3.26	20	187	6.84	4	199	1.36
270-279	5	230	5.82	14	211	5.39	1	220	0.38
280-289	2	258	2.61	5	241	2.20	2	255	0.87
290-299	5	282	7.14	8	252	3.69	2	285	0.97
300-309	2	315	3.19	7	275	3.52	4	326	2.23
310-319	6	341	10.35	6	317	3.47	4	332	2.27
320-329	4	396	8.02	1	400	0.73	5	378	3.23
330-339	2	420	4.25	1	380	0.69	4	395	2.70
340-349	6	442	13.44	2	445	1.63	2	410	1.40
350-359	1	380	1.92	2	450	1.64	5	499	4.26
360-369	3	517	7.84	0	0	0.00	5	505	4.31
370-379	0	0	0.00	1	580	1.06	1	490	0.84

Table 6-11 continued
1997 Electrofishing Data for Brown Trout in Millbrook Marsh Streams

Brown Trout
	Thompson Run			Lower Slab Cabin Run			Upper Slab Cabin Run
Length Group (mm)	Total caught (N)	Mean Weight (g)	g*N (kg)	Total caught (N)	Mean weight (g)	g*N (kg)	Total caught (N)	Mean weight (g)	g*N (kg)
380-389	1	660	3.34	1	640	1.17	0	0	0.00
390-399	1	640	3.24
400-409	1	700	3.54
410-419							1	820	1.40
TOTALS	313		139.72	253		49.87	147		34.97
Biomass	423 kg/ha			106 kg/ha			106 kg/ha
Population estimate and 95% confidence interval	868, 1584, 3843			355, 462, 700			179, 251, 406

Rainbow Trout
Thompson Run		Lower Slab Cabin Run
Length (mm)	Weight (g)	Length (mm)	Weight (g)
106	-	148	35
112	-	152	40
139	35	157	43
149	-
150	40
152	40
157	-
157	50
161	50
166	60
167	55
426	840
452	1070

Species	Common name	Thompson Run	Lower Slab Cabin Run	Upper Slab Cabin Run
Catostomus commersoni	White sucker	2	2	80
Cottus cognatus	Slimy sculpin	63	38	6
Oncorhynchus mykiss	Rainbow trout	13	3	0
Rhinichthys atratulus	Blacknose dace	0	0	10
Salmo trutta	Brown trout	313	253	147
Semotilus atromaculatus	Creek chub	0	0	2
Totals		391	296	245