First records of several sicydiine gobies (Gobiidae: Sicydiinae) frommainland China
Tony H.M. Nip
Asia Ecological Consultants
Limited, 127 Commercial Centre, Palm Springs, Yuen Long, N.T., Hong Kong,
China.
Email: tony_nip@yahoo.com
Date of publication (online): 26 October 2010
Date
of publication (print): 26 October 2010
ISSN
0974-7907 (online) | 0974-7893 (print)
Editor: Heok Hee Ng
Manuscript
details:
Ms # o2439
Received 08
April 2010
Final received
02 August 2010
Finally
accepted 05 September 2010
Citation: Nip, T.H.M. (2010). First records of several sicydiine gobies (Gobiidae: Sicydiinae) from mainland China. Journal of Threatened Taxa 2(11): 1237-1244.
Copyright: © Tony H.M. Nip 2010. Creative
Commons Attribution 3.0 Unported License. JoTT allows unrestricted use of this article in any medium
for non-profit purposes, reproduction and distribution by providing adequate
credit to the authors and the source of publication.
Author
Details: Tony
Nip is currently working for Asia
Ecological Consultants Limited as an ecologist. He has extensive experience in carrying out researches for
fish communities in various environments such as mangrove, stream, river and
shallow sea. Besides, he has also
conducted studies related to aquatic invertebrates and odonates. Although he is mainly working in Hong
Kong, he also conducts surveys in mainland China and
southeast Asia.
Acknowledgements:I would like to thank Dr. M.R.
Leven, P.J. Leader and G.J. Carey, Directors of Asia Ecological Consultants
Limited, for their comment on the draft manuscript and their constant support.
Special thanks are due to Dr. Ni Yong of the East China Sea Fisheries Research
Institute, Chinese Academy of Fishery Sciences and Dr. H.H. Tan of the Department of Biological Sciences,
National University of Singapore for their recommendation. I am also indebted
to Ronald E. Watson of the Agricultural Research Service, United States
Department of Agriculture for his sincere help in fish identification. Last but
not least, I am deeply obliged to Cheng Chi Fai, JianhunLeung, W.W. Chau, H.T. Cheng, Chris Tsoi and Wong David for their assistance in the field, high
quality photos and invaluable information. Without all the help and support
from the aforementioned this study could never have been completed.
Chinese
Abstract: 本研究在華南大陸的河溪進行,共發現了五種瓢鰕虎魚亞科的魚,其中四種為華南大陸新記錄。被發現的種群的數量均十分稀少,有些種更呈極度稀有狀態;當中兩個品種應獲全球性保育關注,餘下的亦至少應獲區域性保育關注。生境破壞,人工改造及污染固然會直接影響這些魚類;但對於數目這麼少的品種而言,商業或私人進行的採集亦為不可忽視的威脅。要保護這些洄游種,河海之間的通道應暢順無阻(如無人為障礙物),河溪流量及環境(如河床)亦要保持自然,而採集行為也應受到嚴格規管。
For figure, images -- click here
Introduction
Sicydiine gobies are amphidromous species
inhabiting clear streams (Keith 2003). In many tropical and subtropical islands a few species are very abundant
and are utilized as food fish by local people (Keith 2003; Lin 2007), although
this kind of harvesting is considered highly unsustainable (Keith 2003). In recent years some colourful species, especially those of the genera Stiphodon, Sicyopterus and Sicyopus, have also become popular in the ornamental fish trade (Ekaratne 2000; Lin 2007; pers. obs., Image 1). Wild-caught individuals are
currently the sole source for this trade, as the reproductive cycle of these
gobies is too complex for breeding on a commercial scale (Keith 2003; Yamasaki
& Tachihara 2006). This form of exploitation, whether by amateur or
professional collectors, has already been considered a threat to these fishes (Ekaratne 2000; Yamasaki & Tachihara2006; Lin 2007). The amphidromous nature of these species also indicates that
they are sensitive to environmental changes, even if the scale of the impact is
slight (Keith 2003; Yamasaki & Tachihara 2006;
Keith et al. 2009). Overall, it is
generally believed that many sicydiine gobies are
highly vulnerable (Keith 2003; Watson et al. 2005; Yamasaki & Tachihara 2006; Keith et al. 2009); many are also believed
to be in danger of extinction (Keith 2003; Watson et al. 2005).
Most sicydiine gobies are found in the Indo-Pacific region (Parenti & Maciolek 1993;
Keith 2003), and new species have usually been described from isolated islands
or island chains (archipelagos) such as the Philippines, Indonesia, Japan and
Vanuatu (Sakai & Nakamura 1979; Watson & Kottelat1995; Watson 2008; Keith et al. 2009). In contrast, few have been recorded from continental landmasses. As an example, four genera of the Sicydiinae have been recorded from Taiwan, namely Lentipes, Sicyopterus, Sicyopusand Stiphodon (Lin 2007; Wu & Zhong 2008). This is compared to only one species ofStiphodon recorded from mainland China (Lee et al.
2004).
The
present study reports the occurrence of five species of sicydiinegobies from mainland China, with four of them being
new records for this area. Besides
providing updated data on the distribution of these species, their dispersion
mode and conservation status are discussed.
Materials
and Methods
During
April to December 2009, 29 small to medium-sized streams (ca. 1-15 m wide)
along the coastal region of Guangdong Province (including Hong Kong), southern
China, were visited (Fig. 1). Fishes
in all streams were surveyed by snorkeling/ direct observation along the
streamside and recorded by waterproof cameras (Sanyo XactiCA8, Canon IXUS 870IS with housing WP-DC26, Canon PowershotG9 with housing WP-DC21, Canon Powershot G10 with
housing WP-DC28, Canon IXY 510IS with housing WP-DC32). Some fishes were also captured
and kept in a small tank for in situ photography and making meristic(primarily fin-ray) counts; all were subsequently released. Most male sicydiinegobies could be easily identified by their colourpatterns (following Watson & Chen (1998); Watson (1999); Nakabo (2000); Chen & Tan (2005); Lin (2007) and Wu
& Zhong (2008)). However, one species could not be readily identified and
high quality photographs of this species were sent to an expert on sicydiine gobies (Ronald Watson) for identification.
Exposing
the exact locations of these fishes would not provide additional information on
their distribution range, but could attract aquarium hobbyists to deplete the
stocks (see result section for the abundances of these fishes). This is contradictory to the purpose of
this study – to understand and help conserving these rare species. Accordingly, no detailed site
information is provided in this paper.
Results
Four Stiphodon species;S. atropurpureus, S. imperiorientis, S. multisquamus and S. percnopterygionus; and
one of Sicyopus (S. zosterophorum) were identified in the material
collected for this study. Except
for S. atropurpureus, these species have not been
previously reported from mainland China. In particular, S. imperiorientis and S. multisquamus were previously thought to be
endemic to Iriomote Island (Japan) and Hainan Island
(China), respectively (Watson & Chen 1998; Wu & Zhong2008). The approximate area where
material was collected for this study is indicated in Figure 1.
Out
of the 29 streams surveyed, S. atropurpureus was observed in seven streams and
fish abundance recorded at each stream ranged from one to 30 individuals. Both males and females were observed. Stiphodon imperiorientis was only observed in one stream
and two males were identified. Although one presumed female of this species was observed in the same
stream, the identity of this individual could not be confirmed. Stiphodon multisquamus was observed in
six streams, and both males and females were identified. However, this species was not as
abundant as S. atropurpureus and fish numbers at each stream
ranged from two to six individuals. Stiphodon percnopterygionus was observed in only one stream by
the author, and a single male was identified. Nevertheless, a local aquarium hobbyist claimed that one
male individual had also been observed in another stream. One very small population (one male and
two females) of S. zosterophorum was observed in a single stream by
the author. Another
population (claimed to be seven individuals) was found by a group of aquarium
hobbyists in another stream. Unfortunately, the latter population is suspected to
be depleted by the persons who discovered them. Descriptions of all these species and a key to the males are
given. Meristiccounts are based on measurement conducted in the present study and information
collected from literatures such as Watson & Chen (1998), Nakabo (2000) and Wu & Zhong(2008).
Stiphodon atropurpureus: D1: VI, D2: I-9, A: I-10, P:
15. The species ranges from 3-5 cm
in total length (TL).
Male:body, snout and cheek iridescent green/ blue/ purple; first dorsal fin not
elongated/ filamentous; first dorsal fin with narrow red margin (Images 2, 3
& 4).
Female: body white/ pale buff with two prominent transverse stripes
(Image 5).
Stiphodon imperiorientis:D1: VI, D2: I-9, A: I-10, P: 15. A large sized fish about 6-7 cm in TL.
Male:pectoral fin spotted; body grey or dark with iridescent blue/ green/ purple
lateral bars; snout and cheek iridescent blue/ green/ purple; first dorsal fin
elongated (Images 6 & 7).
Female: pectoral fin partially spotted; body with two prominent
transverse stripes (no female was identified in the present study, description
is based on illustration from Nakabo (2000)).
Stiphodon multisquamus:D1: VI, D2: I-9, A: I-10, P: 15. A large sized fish about 7-8 cm in TL;
pectoral fin spotted.
Male:upper one-third of body khaki and lower part silvery grey/ grayish brown with
9-10 lateral bars (darker or with a bluish tinge in some individuals); first
dorsal fin elongated and usually slightly filamentous (Images 8, 9, & 10); predorsal midline usually without scales or with very few
scales (Images 11 & 12).
Female: body cream with two transverse stripes, sometimes with dull
lateral bars; dorsum with gold bars; ventrum light blue (Images 13, 14 & 15).
Stiphodon percnopterygionus: D1: VI, D2: I-10, A: I-10, P:
14. The species ranges from 3-5 cm
in TL.
Male: colour highly varied; body, snout and cheek
iridescent blue/ green/ purple; usually with lateral bars (indistinct in some
individuals); first dorsal fin elongated (Image 16);some individuals orange in life (Image 17).
Female: body with two prominent transverse stripes (no female was
identified in the present study, description is based on illustration from Nakabo (2000)).
Sicyopus zosterophorum: D1: VI, D2: I-9, A: I-10, P: 15. The species ranges from 3-5 cm in TL.
Male: anterior half of body dark grey and brown/ yellowish brown, posterior half yellow, green and orange; two thick dark bars on anterior half of body, twomore dark bars below second dorsal fin and one dark bar on caudal peduncle (Image 18).
Female: body light brown without obvious stripe or bar (Image 19).
Discussion
In
general, adults of sicydiine gobies live and breed in
freshwater streams. The
larvae drift downstream passively, and live planktonicallyin the marine environment. When
they reach the post-larval stage, they actively return to freshwater streams
(Fitzsimons et al. 1996; Keith 2003; Yamasaki & Tachihara2006; Yamasaki et al. 2007; Iida et al. 2008). Since these species have a planktoniclarval stage in the sea, ocean currents would play a key role in their
distribution (Keith et al. 2009). For instance, larvae of some sicydiine gobies are believed to be transported from southern regions (such
as the Philippines) to Taiwan/ Japan by the northward-flowing Kuroshio Current (Lin 2007; Yamasaki et al. 2007). The coast of South China has a complex
current system (Morton & Morton 1983). In winter, the current flows from northeast to southwest
along the coast, while the reverse is true in summer. A branch of the Kuroshio Current
also passes through the Luzon Strait and approaches the South China coast. This complex current system may explain
some of the finding of this study: larvae of S. atropurpureus and S. zosterophorum, which mainly appear in the
tropics (Watson & Chen 1998; Watson 1999), would be brought by the Kuroshio Current from tropical regions such as The
Philippines to Guangdong, while S. multisquamus, the species previously thought to
be restricted to Hainan, would be carried to the present study area by the
ocean current prevailing in summer. Given this ocean current system, it is also believed that these gobies
would have a wider range than that observed at present. For instance, besides Guangdong, these
fishes may be found in Guangxi and Fujian (Fig. 1). Indeed, S. atropurpureus is believed to occur in Fujian
(Ronald Watson pers. comm.). Moreover, in view of the present distribution of S. imperiorientis, it is believed that this species
is likely to be found in eastern Taiwan as well.
In
the study area, sicydiine gobies were never found to
be common or abundant and some were very rare. Stiphodon atropurpureus, the most frequently encountered
species, was only found in fewer than a quarter of the streams surveyed. This scarcity may be due to the study
area (Guangdong) being at the periphery of the species distributions. Stiphodon atropurpureus and S. percnopterygionus are widely distributed (Watson
& Chen 1998; Wu & Zhong 2008); the former is
common in the Philippines (Watson & Chen 1998), while the later is fairly
common in southern Japan and eastern Taiwan (Watson & Chen 1998; Yamasaki
& Tachihara 2006). Sicyopus zosterophorum also has a wide range, and has
been recorded in New Caledonia, Indonesia, The Philippines, Taiwan and Japan
(Watson 1999). Even so, the
importance of conserving these species should not be overlooked, and
conservation efforts should be assessed on a regional/ national scale. For example, the Ministry of
Environment, Japan has listed S. atropurpureus and S. zosterophorum as critically endangered, and has
suggested ways to conserve these species, owing to their rarity in Japan
(Ministry of the Environment, Japan 2007, 2010). On the other hand, the present study also indicates that S. imperiorientis and S. multisquamus are still scarce, even though they
have now been shown to have a wider distribution range than was previously
known. Stiphodon multisquamus is considered to be very rare in
Hainan Island, sufficiently so to be considered endangered in China (Wu & Zhong 2008). Watson & Chen (1998) believed that S. imperiorientis is rare as only ten individuals
were collected in their study. This species is also considered to be critically
endangered in Japan (Ministry of the Environment, Japan 2007). Considered in combination with findings
of the current study, it is believed that S. imperiorientis and S. multisquamus should be
considered as of high conservation concern on both regional and global scales,
while other species should at least be of regional conservation concern. Indeed, S. imperiorientis has recently been placed on the
IUCN Red List (IUCN 2010).
During
the present study, many streams were found to be adversely
impacted seriously. Certain
streams have been concreted or channelized, while some have even been filled orculverted. Artificial structures such as dams and pipes to divert stream water for
irrigation or domestic use were commonly seen. Many streams were also found to be receiving untreated
sewage from nearby houses. All
these human-induced impacts are considered serious threats to sicydiine gobies, as they would lead to habitat loss,
increase the sedimentation rate and thus affect the breeding of the fishes, and
block the migration pathway (Fitzsimons et al. 1996; Brasher 2003; Keith 2003;
Yamasaki & Tachihara 2006; McDowall2007; Keith et al. 2009). In order
to protect these species, the flow and environment (i.e. streambed) of the
stream should be kept natural, and the stream-ocean corridor should remain open
(Fitzsimons et al. 1996; Keith et al. 2009). Even in the absence of other conservation measures, avoiding
the aforementioned impacts would be highly beneficial to these species. In addition to environmental
degradation, harvesting activity is considered a threat to these fishes (Ekaratne 2000; Yamasaki & Tachihara2006; Lin 2007). It has been
suggested in Japan that regulations should be set up to strictly control this
kind of activity (Ministry of the Environment, Japan 2010). The Government of Sri Lanka has even
prohibited the trade of certain sicydiine gobies in
order to stop their harvesting for the aquarium trade (Wijesekara& Yakupitiyage 2001). In view of the small population sizes of the fishes
observed, it is considered that they are highly susceptible to overexploitation
and thus similar measures should be adopted in southern China.
Conclusion
This
study provides data indicating that streams in the coastal region of southern
China, even small-sized ones, provide habitats for many sicydiinegobies; and all of them are considered to be of high conservation concern in
mainland China. Two of the species
known from here, S. imperiorientis and S. multisquamus, are considered very rare on a
global scale (Wu & Zhong 2008; IUCN 2010). To protect these gobies, their habitats
(i.e. streams in coastal regions) should be maintained in natural condition,
and man-made environmental impacts on them should be avoided. Also, in view of the rarity of these
species, it is deemed necessary to set up regulations to control harvesting
activities.
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