Journal of Threatened
Taxa | www.threatenedtaxa.org | 26 November 2023 | 15(11): 24255–24260
ISSN 0974-7907
(Online) | ISSN 0974-7893 (Print)
https://doi.org/10.11609/jott.8553.15.11.24255-24260
#8553 | Received 24 May 2023 | Final received 10 September 2023 | Finally
accepted 23 October 2023
Body growth and condition of
endangered Tor putitora (Hamilton, 1822)
(Actinopterygii: Cypriniformes: Cyprinidae)
in the crucially important breeding and nursery grounds of the Ganga stock
Priyanka Rana 1 & Prakash Nautiyal
2
1,2 Aquatic biodiversity Unit,
Department of Zoology, H.N.B. Garhwal University,
Srinagar, Uttarakhand 246174, India.
1 priyankarana.hnb@gmail.com
(corresponding author), 2 pn.mahseer@gmail.com
Editor: Mandar Paingankar, Government Science College Gadchiroli,
Maharashtra, India. Date of publication: 26 November
2023 (online & print)
Citation: Rana, P. & P. Nautiyal (2023). Body growth
and condition of endangered Tor putitora
(Hamilton, 1822) (Actinopterygii: Cypriniformes: Cyprinidae) in the crucially important breeding and nursery
grounds of the Ganga stock. Journal of
Threatened Taxa 15(11):
24255–24260. https://doi.org/10.11609/jott.8553.15.11.24255-24260
Copyright: © Rana & Nautiyal 2023. Creative Commons Attribution 4.0
International License. JoTT allows unrestricted use, reproduction, and
distribution of this article in any medium by providing adequate credit to the
author(s) and the source of publication.
Funding: The present study was funded by the University Grant Commission (UGC) under the Junior Research Fellowship (JRF) scheme provided to the first author.
Competing interests: The authors declare no competing interests.
Author details: Priyanka Rana is currently engaged in the pursuit of her Ph.D. within the Aquatic Biodiversity Unit of the Zoology Department at Hemvati Nandan Bahuguna Garhwal University, located in Srinagar, Uttarakhand. She is working on the reproductive biology of Himalayan Mahseer under the current climatic and land use land cover changes in the Nayar basin of the Ganga River. Professor Prakash Nautiyal is currently affiliated with Aquatic Biodiversity Unit, Zoology Department, Hemvati Nandan Bahuguna Garhwal University, Srinagar Uttarakhand. His area of specialization includes fisheries ecology, conservation ecology of golden mahseer, mountain river ecology, and aquatic biodiversity.
Author contributions: PR conducted the data collection, performed the statistical analysis, and drafted the initial manuscript. PN played a critical role in reviewing and providing constructive feedback on the initial draft and finalized the content for publication.
Acknowledgements:
The authors
acknowledge University Grant Commission, Delhi, India for supporting the study
under the NET-JRF scheme provided to the first author. Authors also acknowledge
the head (PN), Department of Zoology, H.N.B. Garhwal
University, Srinagar, Uttarakhand, India for facilitating successful
accomplishment of work.
Abstract: The study evaluates seasonal
differences in length-weight relationship and relative condition factor (Kn) of Tor putitora
in the Nayar, a critical breeding and nursery ground
in the mountain zone of the Ganga. The growth coefficient of T. putitora varies seasonally between 2.86 and 2.99 while
relative condition factor between 1.00 ± 0.06 to 1.061 ± 0.3. Mahseer shows
negative allometric growth (except the monsoon season) with better condition
factor throughout the study period. The present Kn
factor for different size groups show deviation from past which may be due to
inadequate food resources or excessive fishing in the Nayar.
Keywords: Allometric growth, exploitation,
growth coefficient, isometric, juveniles, Kn,
Mahseer, length-weight, Nayar, spawning.
Introduction
Himalayan Mahseer is an
Endangered (Jha et al. 2018) endemic megafauna of Himalayan rivers that
completes its migratory cycle within glacier-fed and spring-fed tributaries for
spawning/feeding and rearing purposes (Nautiyal 1996;
Bhatt et al. 2000; Nautiyal et al. 2001). Presently,
the mahseer fishery of Indian subcontinent is declining under continuous threat
of indiscriminate fishing, habitat degradation/fragmentation, climate change (Nautiyal 2014) and introduction of non-native fish (Gupta
et al. 2019). The coupled effect of all these factors could be reflected in
their growth, body condition, mortality, and recruitment of the next
cohorts. Length-weight relationship is an
easy tool for the assessment of the body growth and condition of the fish at
the individual as well as population level. The relationship also offers a
measure of the health of the fish population (Safran 1992), as well as a
comparison of the life history characteristics of populations living in various
geo-climatic regions. Various changes in the expected size, length-weight and
hence growth of the fish due to major or minor changes in their life cycle
could be perceived through the length-weight relationship (Le Cren 1951). Further, the relative condition factor (Kn) makes an assessment if increase in the body
weight is in accordance with the desirable reproductive potential and
recruitment rate. The study, therefore, evaluates the present status of the
Himalayan Mahseer stock in the breeding and nursery grounds in the Nayar.
Study area
The Nayar
is a spring-fed perennial river that originates from the Dudhatoli
Hills in the Pauri Garhwal
District of Uttarakhand. The confluence of the Nayar
with the Ganga is located
̴10 km downstream from Devprayag,
Uttarakhand. The stock in the Ganga foothills ascends the Nayar
annually (Nautiyal et al. 2001).
Materials and Methods
The present study was based on
the samples (N = 1966) of Putitor Mahseer collected
from the local fishermen (Image 1) during July 2021 to October 2022 at weekly
intervals. Further, the 1980s data were obtained monthly by the second author
(PN), which contributed to a small sample size compared to weekly collection.
The samples were cleaned with a cotton cloth. Thereafter, the total length and
weight of the individual fish were recorded using measuring tape and a digital
balance respectively.
Length-weight relationship was
estimated using logarithmic form of the following equation
Log W = Log a + b Log L
Where, W is the weight of the
sample in gm, L is the total length of the fish sample in cm while a and b are
the intercept and slope respectively. The regression coefficients and the
length-weight relationship were analyzed using Microsoft Excel 2016 software.
Significance of b value, i.e.,
Ho: ß = 3 was evaluated using t-test as
|b − 3|
t = –––––––
Sb
where, Sb is the
standard error of b.
Relative condition factor was estimated
using
Wo
Kn = ––––
Wc
Where, Wo is the observed weight
and Wc is the calculated weight obtained from
length-weight analysis.
Results
The examined fish samples ranged
from 6.2 to 121.9 cm in the length and 2.1 to 25,000 g in weight, among which
individuals below 25 cm constituted the resident stock of the Nayar (Table 1) as they were recorded throughout the study
period. However, individuals measuring above 25 cm were the migratory brooder
stock of mahseer as they were recorded only during the monsoon season (Table
1). Among the resident stock, the fish measuring between 10–15 cm was high in
total sample followed by 15–20 cm and 20–25 cm.
The seasonal growth coefficient
(b) varied between 2.86–2.99 (Table 2) which is within the expected suitable
range of growth (Froese 1998). Except for the monsoon season (2021), mahseer
has shown negative allometric growth as t-test analysis rejected the hypothesis
i.e., Ho: ß = 3, at
0.05 level (Table 2). However, seasonal analysis of length-weight data of
1980–1981 has shown isometric growth type in winter season while negative
allometric growth type for monsoon and summer season (Table 3). The b value was
estimated as 2.95, for the pooled data of the present stock of mahseer, showing
isometric growth type which was also recorded in earlier studies from the Nayar and other geo-climatic locations (Table 4).
The mean value of monthly
relative condition factor for the present Mahseer cohort ranged between 1.00 ±
0.06 to 1.061 ± 0.3 (Table 5 and Figure 1). The peak of Kn
was observed during monsoon season (July to August) which usually refers their
breeding period as indicated by presence of ripe individuals and
fry-fingerlings (Table 1). Further, a moderate relative condition factor
ranging between 1.003 ± 0.03 to 1.005 ± 0.09 has been observed in between the
monsoon periods. However, the current cohort’s juveniles have a relatively high
relative condition factor, in contrast to the 1980’s cohort, where adults had a
greater Kn factor (Figure 2).
Discussion
The largest size of the Himalayan
Mahseer encountered during this study was 121.9 cm in August. This was
comparatively smaller than the past size (133.7 cm) in 1980–1981 (Nautiyal & Lal 1981). The Mahseer ranging above 40 cm
was very low in number as they are part of migratory stock ascending from Ganga
into Nayar for breeding purposes. However, other
parts of India have also reported a drop in the size of other Mahseer fisheries
and a low share in overall fish catches (Minimol
2000).
The resident 1980’s cohort of the
Nayar (4.1–49 cm) including fingerlings, juveniles
and adults have shown negative allometric growth indicating no significant
weight gain. However, winter season has shown comparable weight gain with
respect to length increment which may be due to availability of food resources
as winter is the most productive period of the Nayar
(Nautiyal 1986). However, negative allometric growth
in 2021–22 cohort throughout the seasons, somehow, indicate depletion of
resources. Additionally, the isometric growth in monsoon and pooled data may be
attributed to inclusion of large sized brooders with ripe eggs in resident
stock (Table 1). Therefore, 1980’s cohort has shown negative allometry in
monsoon season due to prevalence of fingerlings and juveniles (<25 cm) which
do not possess mature gonads. The previous studies on T. putitora
in different regions have also shown isometric, positive and negative allometric
growth patterns with varying geographic and climatic conditions (Table 3).
Therefore, the seasonal fluctuations in sample size, maximum length, gonad
maturity, food availability, feeding intensity (Le Cren
1951) may have played a major role in the body growth and condition of present
cohort of Himalayan Mahseer.
During breeding season large
percentage of the total body weight is influenced by increase in gonad size of
prospective brooders as gonads undergo rapid development during spawning. Hence
Kn attained a peak in monsoon and fell
abruptly thereafter. However, a sudden drop in June may be attributed to the
decline in the feeding intensity from summer onwards (Nautiyal
1996) which coincides with the decline in the food resources from winter afterward.
Similar trend in relative condition factor was observed earlier also and was
used to infer the monsoon as breeding season (Nautiyal
1985). However, in contrast to 1980’s cohort (Nautiyal
1985), the small size groups have shown better fitness while health condition
of adults have deteriorated from past (Figure 1) which may be caused by
overfishing of potential brooders leading to overexploitation, hampered
recruitment, fragmentation of habitat and subsequent degradation, scarcity of
food resources and decline in feeding intensity after attaining a length of 22
cm (Nautiyal 1989). However, low Kn
for juveniles (<20 cm) and comparatively better in adults (> 20 cm) was
recorded form the Khoh, Kolhu,
and Mandal (tributaries of Ramganga) in the Uttarakhand (Atkore
et al. 2007).
Conclusion
The Himalayan Mahseer deviated from the past in
terms of body growth, condition and fitness. The mahseer of present cohort are
not robust compared to past which may be attributed to either lack of food
resources, decline in feeding intensity or increasing fishing pressure.
Although the Mahseer has shown better condition throughout the present study
period but the overall wellness in the adults has declined while inclined in
the juveniles which may be related to habitat suitability or overfishing of
larger size groups. Therefore, this study provides insight about the declined
growth in body size and condition of different size groups of endangered
Himalayan Mahseer.
|
2021 |
2022 |
|||||||||||||
|
Monsoon |
Winter |
Summer |
Monsoon |
|||||||||||
Size-group |
J |
A |
S |
O |
N |
D |
F |
M |
A |
M |
J |
J |
A |
S |
O |
1–5 |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
5–10 |
27.0 |
19.6 |
- |
19.5 |
6.2 |
31.3 |
35.5 |
- |
- |
- |
0.7 |
- |
35.2 |
- |
28.7 |
10–15 |
22.2 |
19.6 |
6.7 |
50.2 |
52.7 |
67.2 |
64.5 |
18.2 |
39.8 |
8.2 |
35.2 |
34.5 |
9.9 |
5.6 |
63.2 |
15–20 |
19.0 |
13.7 |
28.9 |
25.5 |
17.8 |
- |
- |
41.6 |
48.9 |
35.4 |
35.9 |
13.8 |
20.9 |
21.1 |
8.0 |
20–25 |
9.5 |
14.7 |
38.0 |
2.4 |
18.6 |
1.6 |
- |
22.1 |
9.1 |
45.6 |
22.1 |
17.2 |
8.8 |
32.2 |
- |
25–30 |
7.9 |
8.8 |
15.1 |
0.4 |
3.1 |
- |
- |
5.2 |
- |
8.8 |
6.2 |
13.8 |
6.6 |
22.2 |
- |
30–35 |
1.6 |
3.9 |
4.9 |
- |
1.6 |
- |
- |
7.8 |
- |
1.4 |
- |
6.9 |
1.1 |
5.6 |
- |
35-40 |
3.2 |
4.9 |
1.8 |
0.8 |
- |
- |
- |
- |
0.4 |
0.7 |
- |
3.4 |
3.3 |
3.3 |
- |
40–45 |
- |
2.0 |
0.4 |
1.2 |
- |
- |
- |
2.6 |
1.3 |
- |
- |
- |
5.5 |
3.3 |
- |
45–50 |
1.6 |
4.9 |
0.4 |
- |
- |
- |
- |
1.3 |
0.4 |
- |
- |
6.9 |
3.3 |
2.2 |
- |
50–55 |
1.6 |
2.9 |
0.4 |
- |
- |
- |
- |
1.3 |
- |
- |
- |
- |
2.2 |
1.1 |
- |
55–60 |
1.6 |
1.0 |
0.4 |
- |
- |
- |
- |
- |
- |
- |
- |
- |
1.1 |
2.2 |
- |
60–65 |
1.6 |
1.0 |
0.4 |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
65–70 |
- |
1.0 |
0.7 |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
70–75 |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
1.1 |
- |
75–80 |
1.6 |
1.0 |
0.4 |
- |
- |
- |
- |
- |
- |
- |
- |
3.4 |
2.2 |
- |
- |
80–85 |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
85–90 |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
90-95 |
1.6 |
- |
0.4 |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
95–100 |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
100–105 |
- |
- |
0.4 |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
105–110 |
- |
- |
0.4 |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
110–115 |
- |
- |
0.4 |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
115–120 |
- |
- |
0.4 |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
120–125 |
- |
1.0 |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
- |
Season |
N |
Total length (cm) |
Total Weight (gm) |
a |
b |
r2 |
T0.05 |
Growth * |
||
Min. |
Max. |
Min. |
Max. |
|||||||
Monsoon |
700 |
7.5 |
121.9 |
4 |
25000 |
-2.07 |
2.99 |
0.99 |
0.84 |
I |
Winter |
224 |
8.9 |
34.1 |
6.65 |
362.64 |
-1.97 |
2.91 |
0.99 |
4.64 |
NA |
Summer |
745 |
15 |
51.2 |
34.01 |
1167.16 |
-1.89 |
2.86 |
0.98 |
4.63 |
NA |
Monsoon |
297 |
6.2 |
78.9 |
2.1 |
5000 |
-1.98 |
2.91 |
0.98 |
4.21 |
NA |
Pooled |
1966 |
6.2 |
121.9 |
2.1 |
25000 |
-2.01 |
2.95 |
0.97 |
1.77 |
I |
* t—t-test | I—Isometric |
NA—Negatively allometric.
Season |
N |
Total length (cm) |
Total weight (gm) |
a |
b |
r2 |
T0.05 |
Growth * |
||
Min. |
Max |
Min. |
Max |
|||||||
Monsoon |
59 |
4.1 |
25 |
0.548 |
113.5 |
-2.00 |
2.88 |
0.98 |
2.30 |
NA |
Winter |
134 |
4.9 |
21.6 |
1.025 |
83 |
-1.98 |
2.91 |
1.00 |
0.49 |
I |
Summer |
52 |
7.1 |
49 |
2.98 |
875.5 |
-0.12 |
1.33 |
0.68 |
2.35 |
NA |
* t—t-test | I—Isometric |
NA—Negatively allometric.
River/Other |
State |
b |
Growth * |
Reference |
Nayar |
Uttarakhand |
2.88 |
I |
Lal & Nautiyal
1980 |
Nayar |
Uttarakhand |
2.98 |
I |
Nautiyal 1985 |
Pong Reservoir |
Himachal Pradesh |
3.15 |
PA |
Johal et al. 2005 |
Ladhiya |
Uttarakhand |
2.99 |
I |
Patiyal et al. 2010 |
Jia Bharoli
|
Arunachal Pradesh |
3.108 |
I |
Ali et al. 2014 |
Beas |
Himachal Pradesh |
3.082 |
I |
Ali et al. 2014 |
* I—Isometric | PA—Positive
Allometric | NA— Negatively Allometric.
Month |
N |
Kn ± S. D. |
July |
63 |
1.013 ± 0.16 |
August |
102 |
1.015 ± 0.18 |
September |
284 |
1.009 ± 0.13 |
October |
251 |
1.004 ± 0.08 |
November |
129 |
1.003 ± 0.08 |
December |
64 |
1.003 ± 0.08 |
February |
31 |
1.003 ± 0.08 |
March |
77 |
1.004 ± 0.09 |
April |
231 |
1.003 ± 0.08 |
May |
147 |
1.003 ± 0.08 |
June |
290 |
0.954 ± 0.09 |
July |
29 |
1.061 ± 0.30 |
August |
91 |
1.027 ± 0.31 |
September |
90 |
1.005 ± 0.11 |
October |
87 |
1.002 ± 0.06 |
Pooled |
1966 |
1.013 ± 0.16 |
For
figures & image - - click here for full PDF
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