Effects of Incubation Method and Transfer Timing on the Hatching Rate of Fertilized Eggs of the River Puffer Takifugu obscurus

124

Copyright © 2021 The Korean Society of Fisheries and Aquatic Science pISSN:0374-8111, eISSN:2287-8815

서 론

복어류는전세계적으로

120

여종이분포하고있으며이중식 용으로이용하는산업종은황복

(Takifugu obscurus),

^자주복

(T.

rubripus),

^참복

(T. chinensis)

^{등을포함하여}

10

여종에불과하 다

.

황복은복어목

(Tetraodontiformes)

^{의 참복과}

(Tetraodonti- dae)

에속하며우리나라의서해연안과기수역

(

임진강

,

한강

,

금 강

,

만경강

),

동중국해및남중국해와인접한강하류

(

랴오허

,

황 허

,

^양쯔강등

)

^{에분포하며}

,

^{우리나라와중국의황해로유입되} 는하천의중

·

상류지역까지서식하는광염성해산어류에속한 다

(Yuan and Xie, 1986; Wang, 2008).

황복은서식수온이

15-22°C

내외인온대성어종이나다른복 어류와는달리바다에서성장후하천수온이

15-20°C

에도달하 는

4

^월중순

-6

^{월초순경에산란을위해임진강}

,

^한강

,

^만경강등

서해안하천으로거슬러올라와산란을하는소하성어류이다

.

황복의식성은잡식성이나어린시기에는성어와달리부유동물 과소형의치어를먹으며

,

성어가되면새우

,

권패류

,

조개류

,

곤 충의유충

,

^{지각류와고등식물의잎사귀등긴모양의조개류등} 을먹는것으로알려져있다

(NIFS, 2006).

국내의황복연구는배란유도방법

(Jang, 1996),

난발생과자

·

치어발달에관한연구

(Jang et al., 1996),

세포유전학적연구

(Park et al., 1997),

정자의냉동보존및해동기술

(Chang et al., 1999),

^{초기단계의소화효소변화}

(Son et al., 2001),

^급격한염 분변화에 따른생리적변화

(Lee and Kim, 2005),

백점충감 염

(Park et al., 2004),

수온이성장과혈액에미치는영향

(Lee et al., 2004),

초기발달시기먹이와염분의효과

(Kang et al.,

2004)

등이보고되었다

.

국외연구는인공종자생산연구및무

독화담수양식

(Jiang et al., 2000), LHRH-a

^{를이용한산란유도}

황복(Takifugu obscurus) 수정란의 부화방법 및 수송 시기에 따른 부화율 조사

유광열·허준욱 ¹ *

특허청 식품생물자원심사과, ¹군산대학교 해양생명응용과학부

Effects of Incubation Method and Transfer Timing on the Hatching Rate of Fertilized Eggs of the River Puffer Takifugu obscurus

Gwangyeol Yoo and Junwook Hur

¹

*

Food & Biological Resources Examination Division, Korean Intellectual Property Office, Daejeon 35208, Korea

1Faculty of Marine Applied Biosciences, Kunsan National University, Gunsan 54150, Korea

This study was conducted to evaluate the effects of incubation methods and transfer timings on the hatching rate of fertilized eggs of the river puffer Takifugu obscurus . Four incubation methods were tested, a) control (fertilized eggs attached to the glass plate), b) bottom (fertilized eggs spread on the bottom of the tank without any treatment), c) S-bottom (removing the stickiness of the fertilized eggs, and then spreading the eggs on the bottom of the tank), and d) incubator (removing the stickiness of the fertilized eggs, and then incubating the eggs in an incubator). Ad- ditionally, four transfer timings were tested: a) control (no transfer from the incubation tank), b) zygote (fertilized eggs transferred at the zygote stage), c) segmentation (fertilized eggs transferred at the segmentation stage), and d) pharygula (fertilized eggs transferred at the pharygula state). The results showed that the hatching rate of incubator was significantly higher than those of control, bottom, and glass (P<0.05). The results also showed that the hatching rates of control and pharygula were significantly higher than those of zygote and segmentation (P<0.05).

Keywords: Puffer, Hatching rate, Incubation method, Transfer timing, Adhesiveness

*Corresponding author: Tel: +82. 63. 469. 1838 Fax: +82. 63. 469. 7442 E-mail address: [email protected]

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial Licens (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Received 30 December 2020; Revised 14 January 2021; Accepted 21 January 2021 저자 직위: 유광열(심사관), 허준욱(교수)

https://doi.org/10.5657/KFAS.2021.0124

Korean J Fish Aquat Sci 54(1), 124-128, February 2021

부화방법 및 수송시기에 따른 황복 수정란의 부화율

125

(Yang and Chen, 2004),

^{광주기변화에따른난발생}

(Yang and Yang, 2004),

삼투압조절

(Kato et al., 2005),

급격한염분변화 에따른삼투압반응

(Yan et al., 2005),

난발생에미치는수온과 염분의영향

(Yang and Chen, 2006)

등대부분생리분야에관한 연구가수행되어있다

.

양식현장에서황복의종자생산은수정란을수조바닥에살포 하거나수정란의부착성질을이용하여유리판에수정란을부 착시키는방법들로이루어지고있다

.

그러나상기방법들은수 정란의관리가어렵고유리판에수정란의부착밀도를조절하기 가매우까다로워다년간의숙련된기술및많은인력이요구되 는가하며

,

^{또한부착및살포밀도에따라부화율의편차가매우} 크다

.

특히

,

많은양식장에서황복수정란을수조바닥에그대로 수용하여부화될때까지관리하고있는데

,

이러한방법은생존 율이낮기때문에황복친어도많이필요할뿐만아니라다수의 사육지에수정란을관리하게되므로수조관리

,

사육수가온비 상승등의문제로비효율적이라할수있다

.

^{또한국내에주요} 양식대상품종으로자리잡은넙치

,

감성돔

,

송어등은전문적 인어미관리업체에서수정란을생산하여종자생산업체에공 급하고있는데

,

아직까지대부분의황복양식장에서는자연산 어미를이용하여종자를생산하고있다

.

이러한기술개발의한 계로황복의양식생산량증대를기대하기가어려운실정이다

.

따라서본실험은안정적인황복종자생산을위해기존에수 정란부화방법이외에새로운부화방법을찾고자수행하였으 며

,

또한현장에서수정란을확보하여어느시기에양식장

(

부 화장

)

으로수송해야생존율을 높일수 있는지알아보고자수 행하였다

.

재료 및 방법

수정란 확보

성숙한

4

^{년생양식산어미황복}

13

^마리

(

^평균중량

379±14.6 g

의암컷

9

마리

,

평균중량

285±9.64 g

의수컷

4

마리

)

로부터

채란및채정하여

,

인공수정후수정란을

500 μm

의나일론망

에담아여과살균수

(

염분

4.5 psu,

수온

20°C)

로

5

분간세척

(

세 란

)

한후실험에이용하였다

.

확보한수정란은

375,200

립으로 수정율은

97%

^{로실험에이용하기전고르게혼합하여사용하} 였다

.

수정란 부화방법에 따른 부화율 평가

황복수정란의적정부화관리방법을규명하기위하여수정 란을유리판에부착시키는실험구를대조구

(control)

로선정하 였으며

,

^{수정란을아무런처리없이수조바닥에살포하는실}

험구

(bottom),

수정란의점착성질을제거후수조바닥에살포

하는실험구

(S-bottom)

및수정란의점착성질을제거후부화

기를이용한실험구

(incubator)

로

4

가지방법별부화율을조사 하였다

.

모든실험구는

3

반복으로설정하였으며

,

실험수조는

2

ton

의원형

FRP (fiber reinforced plastics)

수조

(

지름

150 cm,

높이

120 cm)

^{를사용하였다}

. Control

^은

40×60 cm

^의유리판 에

15,000

립의수정란을부착시킨후수조에수용하고

, bottom

실험구는수정란에아무런처리없이수조에

15,000

립씩고루

살포하였다

. S-bottom

실험구와

incubator

실험구의점착성질

제거를위해수정란확보전에원뿔형용기

(

지름

30 cm,

높이

50 cm)

^{를준비하여용기안에사육수를}

50%

^채우고

,

^에어스톤 을용기하부에배치하여사육수가충분히교반되도록한후점 토분말인

Fuller’s earth (catalog no. f200, Sigma-Aldrich, St.

Louis, MO, USA) 10 g

을넣고수정란

50,000

립을수용하였다

.

용기안에수정란을수용하고

10

초간교반시킨후용기안의내 용물을나일론망

(500 μm)

^{에옮겨담아흐르는물로}

3

^분간세 란하였다

. S-bottom

실험구는수정란을세란후수조에

15,000

립씩수용하였으며

, incubator

실험구는

1 L

용량의원뿔형플 라스틱부화기에

15,000

립씩수용하였다

(Fig. 1).

모든실험구 의사육수는수온

21±0.46°C,

염분

4.57±0.04 psu,

유수량

4 .0 L/min

^{로관리하였다}

.

^{부화수량파악을위해부화직후부터}

5

일동안

control, bottom,

및

S-bottom

실험구는매일야간에

15

회씩

1 L

의용기에사육수를채취하여용기안의자어수량을계 수후수조에수용된사육수량으로환산하였고

, incubator

실험

구는부화기배출관하부에

500 μm

의나일론망으로제작한포

획망을설치하여육안으로계수하였다

. 수정란 수송 시기에 따른 부화율 평가

수정란수송시기에따른부화율평가를위해수정란을운송 하지않고부화관리하는실험구를대조구

(conrol)

로선정하고

,

수정직후

(zygote),

체절형성기

(segmentation,

수정후

70

시간

)

및

60%

^{이상의개체에눈이뚜렷하게착색되는시기}

(pharygu- la,

수정후

100

시간

)

에

3

시간동안수정란을각각수송하여부 화율을비교하였다

(Fig. 2).

수정란은실험구당

1 L

용량의원뿔 형플라스틱부화기

3

개에

15,000

립씩수용하였다

.

모든실험 구의수정란은실험

1

과동일한방법으로점착성질제거하고세 란후수송또는부화기에수용하여관리하였다

.

^{수정란의운송} 은

20 L

의투명비닐봉투에사육수

(

염분

4.45 psu,

수온

21.0°C)

10 L

를넣고수정란을

15,000

립씩수용한후산소를충전하고

밀봉하였으며

,

밀봉된봉투를승용차량에적재하고

3

시간동안 Fig. 1. Cone incubator. a, Imhoff cone; b, glass bead; c, inlet; d, outlet.

a b c

a d

b c

b

c c

a

0 20 40 60 80 100

Control Bottom S-bottom Incubator

Hatching rate (%)

a

b b

a

0 20 40 60 80 100

Control Zygote Segmentation Pharygula

Hatching rate (%)

유광열

ㆍ

허준욱

126

수송후부화기에다시수용하여부화율을평가했다

.

모든실험 구의사육수는수온

21±0.39°C,

염분

4.48±0.04 psu,

유수량

4 .0 L/min

^{로관리하였다}

.

^{부화자어수파악을위해배출관하}

부에

500 μm

의나일론망으로만든포획망을설치하여육안으

로계수하였다

. 통계처리

실험구별부화율은

SAS (Version 9.1)

프로그램을이용하여

One-way ANOVA

^{로통계분석하였다}

.

^{데이터값은최소유의}

차

(least significant difference test, LSD)

검정

(P<0.05)

으로비 교하고평균값

±

표준편차

(mean±SD)

로나타냈다

.

결과 및 고찰

황복수정란의부화방법에따른부화율은

Fig. 3

에나타내었

다

.

부화율평가결과

control, bottom, S-bottom

및

incubator

의부화율은각각

61.7±6.81%, 33.2±5.62%, 41.8±3.76%

및

83.4±2.59%

^로

incubator

^{실험구의부화율이다른모든실} 험구에비해유의한차이로높게나타났으며

(P<0.05), control

의부화율은

bottom

및

S-bottom

실험구에비해유의한차이 로높게나타났다

(P<0.05).

그러나

bottom

과

S-bottom

실험구 간에는유의한차이가나타나지않았다

(P>0.05).

점착성수정 란의부화관리방법은수정란을적당한기질에부착시켜관리 하는방법과수정란의점착성질을제거한후부화기에수용하 여유동식으로관리하는방법으로구분할수있다

(Kitsukawa et al., 2006; Mizuno et al., 2013).

수정란의점착성질을제거 하면수정란이서로엉겨붙지않아산소결핍에따른사란의 발생을방지할수있고

,

^{이로인해부화율이향상된다고빙어}

(Mizuno et al., 2013),

대구

(Gwak et al., 2010),

은어

(Kitsu- kawa et al., 2006)

등다양한어종에서보고되었다

.

수정란의 점착성질제거방법은수정란을탄닌산용액에침지하는방법

(Tanaka, 2008),

가리비패각이나카올린분말이혼합된용액

에침지하는방법

(Kudoh, 1999; Mizuno et al., 2010),

^녹차추 출물이혼합된용액에침지하는방법

(Mizuno et al., 2013)

등 다양한방법들이보고되었다

.

본연구에서는수정란을점토분 말인

Fuller’s earth

가혼합된용액에침지한후부화기에수용 하여유동식으로관리한실험구가다른모든실험구들에비해

유의한차이로부화율이높게나타났다

(P<0.05).

실험구별부 화까지소요시간은

control, bottom, S-bottom

및

incubator

에 서각각수정후

158.5

^시간

, 176.3

^시간

, 182.3

^시간및

149.7

^시 간에관찰되었다

.

부화까지소요되는시간도

S-bottom

실험구 가

control

과

incubator

에비해장시간소요되는반면

bottom

과 는유사하게나타났다

.

이러한결과는

incubator

실험구는수정 란을부화기를이용하여유동식으로관리하여난막에부착된

Fuller’s earth

^{가제거되는반면}

S-bottom

^{실험구는난막에부착} 된

Fuller’s earth

가탈락되지않음으로인해수정란에산소가원 활하게공급되지않았기때문으로추정된다

.

황복수정란의수송시기에따른부화율은

Fig. 4

에나타내었

다

.

부화율평가결과

control, zygote, segmentation

및

pharygu- la

^{의부화율은각각}

81.2±4.16%, 46.8±8.60%, 55.3±5.87%

및

79.8±3.51%

로

, control

과

pharygula

실험구의 부화율이

zygote

실험구와

segmentation

실험구에비해유의한차이로 높게 나타났다

(P<0.05).

그러나

control

과

pharygula

실험구

, zygote

실험구와

segmentation

실험구간에는유의한차이가나 타나지않았다

. Jang et al. (1996)

^{은황복의난발생과정을융} 합기

(zygote period),

난할기

(cleavage period),

포배기

(blastula period),

낭배기

(gastrulla period),

체절형성기

(segmentation

Fig. 2. Developmental stages on transfer timings of fertilized eggs

of river puffer Takifugu obscurus. a, zygote period; b, segmenta- tion period; c, pharygula period.

a b c

a d

b c

b

c c

a

0 20 40 60 80 100

Control Bottom S-bottom Incubator

Hatching rate (%)

a

b b

a

0 20 40 60 80 100

Control Zygote Segmentation Pharygula

Hatching rate (%)

Fig. 3. Hatching rate according to incubation methods. Values with different letters are significantly different (P<0.05). Values are means±SD (n=15).

a b c

a d

b c

b

c c

a

0 20 40 60 80 100

Control Bottom S-bottom Incubator

Hatching rate (%)

a

b b

a

0 20 40 60 80 100

Control Zygote Segmentation Pharygula

Hatching rate (%)

Fig. 4. Hatching rate according to transfer timings. Values with different letters are significantly different (P<0.05). Values are means±SD (n=15).

a b c

b c

b

c c

a

0 20 40 60 80 100

Control Bottom S-bottom Incubator

Hatching rate (%)

a

b b

a

0 20 40 60 80 100

Control Zygote Segmentation Pharygula

Hatching rate (%)

부화방법 및 수송시기에 따른 황복 수정란의 부화율

127

period),

^{인두형성기}

(pharygula period),

^부화기

(hatching peri- od)

등

7

개의범주로나누었으며

, 17°C

수온에서체절형성기와 인두형성기는수정후

55

시간

, 137

시간후에각각관찰되고

,

수 정후

260

시간부터는부화가시작된다고보고하였다

.

본연구 의

control

의체절형성기와인두형성기는

36

시간

, 78

시간후에 각각관찰되었고

,

^수정후

148

^{시간부터는부화가시작되었다}

.

이러한결과는

Jang et al. (1996)

이보고한

17°C, 22°C

및

25°C

의수온에서황복수정란부화시간은수온이높을수록짧고

,

부 화율은수온이낮을수록높았다는연구결과와유사하였다

.

한 편

control, zygote, segmentation

및

pharygula

의실험구별부 화까지소요시간은

148

^시간

, 174.6

^시간

, 156.5

^시간및

148.5

^시 간으로

,

수정란의발생이더욱많이진행된시점에수정란을수 송할수록부화까지소요시간이단축되는경향을보였다

.

따라서황복수정란의부화율향상을위해점착성질을제거 후부화기를이용하여관리하고

,

수정란의수송은안점형성후 수송하는것이바람직할것으로판단된다

.

^{앞으로황복종묘생} 산기술의안정적인정착을위해수정란의수송밀도별

,

부화기 에수용밀도별부화율평가

,

수정란운송시기별부화시간평가 에관한연구들이수행되어야할것으로판단된다

.

사 사

본연구는농림수산식품부수산실용화기술개발사업

(311045- 03-1-SB010)

의지원에의해수행되었습니다

.

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